Understanding the coordinate system is essential to understanding the way AutoCAD works. In AutoCAD, you can assign length and angles, as well as coordinate values, to make drawings, but to do all this, knowledge of the coordinate system is essential.

Primarily, these are two types of coordinate systems that we will use to make geometries in AutoCAD, and they are Cartesian and polar coordinates. First let's have a look at what Cartesian coordinates are.

AutoCAD follows the Cartesian coordinate system, which is a graphical method of assigning coordinates to a point in space. The simple three-dimensional space has three coordinates, namely X, Y, and Z, which are mutually perpendicular to each other, as in the following diagram. The point of intersection of the three mutually perpendicular axes is the origin, which is represented as (0,0,0):

The position of any point in a three-dimensional space can be specified using these three axes, which are represented by the X, Y, and Z axes in the preceding diagram. But for a two-dimensional space, we only need to use the X and Y axes to define the position of any point.

In a two-dimensional space, the simple (X,Y) coordinate system is used and any point in a two-dimensional space can be defined using these two coordinates only. Take the example of the following graph. Here, the origin is mentioned as (0,0), which is also the point of intersection of the X and Y axes, represented by horizontal and vertical lines, respectively:

The A (7,8) point is at 7 units from the origin along the X axis and at 8 units along the Y axis. Similarly, the B (-6,3) point is at 6 units along the negative side of the X axis and at 3 units along the positive side of the Y axis. In the case of the C (4,-5) point, the distance from the positive side of the X axis is 4 units, and its distance along the negative side of the Y axis is 5 units.

The X axis points to the right of the origin are positive and the points to the left of the origin are negative. Similarly, on the Y axis, the points on top of the origin are positive and the points below the origin are negative.

Using polar coordinates, we can also represent points in a two-dimensional space. In this case, one polar distance and an angle with respect to the X axis are required instead of the X and Y coordinate values. To understand this clearly, have a look at the following graph:

In this case, the B point is represented by (8<30), where 8 is the distance between the A and B points. Here, A is the origin and 30 is the angle between line AB and the positive X axis in an anticlockwise direction.

This type of coordinate representation, where a point in space is represented by an angle with respect to the positive X axis and the distance from the origin, is known as a polar coordinate system.

Throughout this book, we will use both methods of coordinates to make our drawing. Drawings in AutoCAD are not essentially made only with coordinate values. For most of the cases, we use a general approach of direct distance entry and we use coordinates only in specific situations.

In the next section, we will start making our first drawing with the Line command using direct distance entry as well as different coordinate values.

You can select the Line command from the command bar, using its command alias, or you can also select the command from the ribbon panel. The Line command will make a straight-line segment of any specified length. This is the most basic of the draw tools and one of the most frequently used ones in the drawing workflow.

The Line command is in the Draw panel of the Home tab. To start the command, you need to left-click on its icon once or you can use its command alias, L. In this case, let's start the Line command from the ribbon panel:

Once your command is active, you will notice that the cursor will change into a point selection cursor that looks like two perpendicular intersecting lines and the command line will also show the name of the command, along with the prompt, as shown in the following screenshot:

Now, AutoCAD is ready for your input and you can start making the line. To do that, perform the following steps:

1. Click on any point in the drawing area and the line will start from that point. Move your cursor and you will notice that the line will follow the movement of the cursor and it will stretch with the cursor, too. This line is also called a rubber bending line, which follows your cursor.
2. Click on a second point in the drawing area and the fixed-length segment of the line will be made and the rubber bending line will again follow from the last point where you clicked. Repeat the process to make additional lines, and when you are done making the geometry, press the Enter or Esc key to exit the command.

This is the general workflow for making a random curve in AutoCAD but, as you have noticed, this method lacks precision as the distance was not specified for the line. To make drawings with precise distances, you need to use the direct distance entry method, which is explained in the next section.

In AutoCAD, direct distance entry is the most obvious way of making lines of precise length. This method is fairly easy, too. To explain this method, I will make a rectangle with a length of 7 units and a width of 5 units using the direct distance entry method and a line tool, as in the following example:

1. Select the Line command from the Draw panel of the Home tab, as in figure 2.4, or type L and press Enter to start the command using its command alias.
2. The command line will prompt you to specify the first point, as in figure 2.5. Click anywhere in the drawing area to add the first point of the line and let go of your mouse cursor and move your mouse elsewhere. The rubber bending line will be formed starting from the first point.
3. Move your cursor in a horizontal direction and type a distance value. In this case, type 7 and press the Enter key again.
4. The line will be formed in a horizontal direction with a length of 7 units.
5. Now, move your cursor in an upward direction and again type another value. In this case, type 5 and press Enter. Another line in a vertical direction with a length of 5 units will be formed.

6. Move your cursor again to the left, type 7, and press Enter again to make another horizontal line.
7. Move your cursor down, type 5, and press Enter again. The line will return back to the starting point.
8. The command will still continue and you will have a rubber bending effect of the line. Press the Enter or Esc key to exit from the Line command.

Once you are done with all the previous steps, you will have a rectangle that looks like the following screenshot. In this rectangle, the length is 7 units and the width, or height, is 5 units:

This direct distance method is generally used to make drawings in AutoCAD and, as you have noticed, it allows you to make precise drawings as well. A similar workflow can also be used to make other geometries.

There are other methods of making drawings in AutoCAD and we will discuss these in the next section.

Let’s take the example of this triangle shown here. In this case, all three coordinates of this triangle are labeled as point A, B, and C:

We will make this triangle in the following example using the Line command, but instead of direct distances, we will use coordinate values:

1. Select the Line tool from the Draw panel or use its command alias, L, to start the command.
2. The command line will prompt you to specify the first point for the line, as in figure 2.5. Type 0,0 for the first coordinate point, which is also the A point of the triangle, and press Enter.
3. Now, we need to specify the coordinates of the second point, B. Type 10,0 and press Enter again. The cursor will move to the B point of the triangle.
4. Once again, we need to specify the coordinates of the next point, C. So, type 14,7 and press Enter.
5. Now, our cursor is at the C point and you can simply type 0,0 and press Enter to return to the first point, which is the origin. To exit the command, press the Enter or Esc key once.

As you have noticed, we only required the coordinates to make this triangle, but the coordinates are rarely used for making drawings and, in most cases, the length and angle values are predominantly used. In real-world drawings too, we will use direct distance entry primarily, but there will be a few instances where coordinates will also be used to make drawings.

In the next example, we will learn how to make a simple drawing using the polar coordinate system.

Using polar coordinates, you can add distance and angle values directly to the command line and they need not be entered separately. To explain this, I will use the following diagram:

In this case, we need to draw a line that is inclined at an angle of 36 degrees with respect to the positive side of the X axis and has a length of 6 units. The following is the workflow for making this line:

1. Type L and press Enter to start the line command.
2. Type 0,0 and press Enter to start the line from the origin.
3. Type 6<36 in the command line and press Enter.
4. The line with a length of 6 units and a 36 degree angle with respect to the X axis will be made.

In this case, we started the line from the origin, and the distance from point A to point B is 6 units and the angle this line makes with respect to the positive side of the X axis is 36 degrees. So, you can add both of these values in the polar coordinate to form a DIS<ANG format, where DIS is the distance and ANG is the angle.

If, however, you start the line not from the origin, but from a random point in the drawing area and still want the same result, then you need to add an @ sign before the polar coordinates. This method is known as the relative coordinate system, which is explained next.

To explain the relative coordinate system, I will once again use the same diagram that we used in the previous section, but in this case, the line will not start from the origin. Rather, we will start it randomly from any point in the drawing area, as in the following diagram:

So, the same line with a length of 6 units that is not starting from the origin and has an inclined angle of 36 degrees can be made using the following workflow:

1. Type L and press Enter to start the line command.
2. Click on any point in the drawing area to start the line.
3. Type @6<36 in the command line and press Enter.
4. The line with a length of 6 units and a 36 degree angle with respect to the X axis will be made.

This @ sign represents the relative coordinate system, which allowed us to make a line from a point that is not on the origin. Here is another example of relative coordinates.

As explained in the previous example, relative coordinates are helpful when you are making a drawing from a point that isn't the absolute origin and still want to use the selected point as a reference for adding the coordinates. In this example, I will create the following triangle using relative coordinates:

Here, you can start the drawing at point A, which is not on the origin, and then progressively make your drawing by entering distances. Instead of direct distances, however, we will use relative coordinates to make this triangle in the following example:

1. Start by selecting the Line command and then click on a point in the drawing area, making sure that the point is not at the origin. Let’s call it point A. As the A point is chosen randomly, we can’t specify an exact value of the (X,Y) coordinate for the B point with respect to the A point. So, in this case, we can use relative coordinates to specify a coordinate value of the B point with respect to the A point. Relative coordinates assume that the last point you clicked or selected is the origin and then make all measurements from that last point as if that point were the origin.
2. So, if point A were the origin, then point B should be 8,0, with respect to point A. To make the AB horizontal line, type @8,0 and press Enter. The line will end up at point B, as in figure 2.10. Note the @ sign before the coordinate value. This @ sign is added to indicate that the next coordinates are "relative" with respect to the point that we previously clicked, which is the A point, in this case, and it will assume the A point as the origin instead of the absolute origin of the drawing.
3. Once you have reached point B, don’t exit the line command, but type @0,6 and press Enter. You will notice that AutoCAD will reach point C, as in figure 2.10, and in this case, the B point will also be treated as the origin and the coordinate value of the C point with respect to the B point is 0,6, which is shown with the @ sign.
4. You can complete the triangle by clicking again on the A point and then pressing Enter to exit the line command.

So, now that we have seen different methods of making the drawing in AutoCAD, let’s use a combination of these methods to make a simple drawing.

So far, we have used different coordinate systems to make a drawing, but it is generally not the ideal way of making drawings in AutoCAD. Generally, we would use direct distances and angles instead. In this section, we will learn how to use this method to make drawings. To explain this example, I will use this triangle:

In this drawing, there is no coordinate information provided and we will use only the dimension values, such as the length and angle, provided here to make it. We will make this triangle performing the following steps:

1. Open a blank drawing and start the line command by clicking on the Line tool in the Draw panel, or by using the L command.
2. Click at a point in the drawing area to start the rubber bending line and move your cursor toward the right side. Type 10 in the command line and press Enter.
3. Press Enter again to exit the command.

4. Click again at the starting point of the line (point A) and type <30, and then press Enter. Notice the < angle sign before 30. In this case, entering the angle sign before 30 will tell AutoCAD to take the numeric value as an angle and not a distance. Once you press Enter, you will notice that the line will be locked at an angle of 30 degrees with respect to the positive side of the X axis.
5. Move your cursor in the direction of the 30 degrees line and type 14, and then press Enter again. This will make a line at an angle of 30 degrees with a length of 14 units.
6. Click on the B point, as in the preceding diagram, and press Enter again to exit the command.

In this case, you saw that geometry can also be made by entering values of the distance and angle directly in the command line. This method is relatively easy when compared to the coordinate entry method. This is also the most common way of making drawings in AutoCAD. There are also some status bar modes that help you to generate references that can be used to make precise drawings. These modes are Dynamic Input, ortho, and polar tracking, and we will discuss them in the next section.

The status bar modes help you make precise drawings in AutoCAD. The tools in the status bar can be toggled on and off by clicking on their icons or by using their function keys. Not all status bar icons are visible by default and you can toggle the visibility of the icons as per your requirements:

To change the visibility of icons in the status bar, click on the customization icon, shown as three dashes on the far-right side of the status bar, and click on the name of the icon that you want to show on the status bar. When visible, a checkmark will show next to the icon's name. In the following screenshot, you can see Dynamic Input and other status bar toggles checked in the customization menu:

In this section, we will discuss some of the most basic status bar toggles that we need in order to render drawings precisely.

Dynamic Input allows you to enter the distances, angles, and other values right inside a drawing with a visual reference. Using the Dynamic Input tool, you can bypass the command line and enter the details directly in the drawing.

To explain the Dynamic Input tool, I will again use the drawing of an inclined line shown in the following diagram:

Here, we will make our inclined line with a length of 6 units and an angle of 36 degrees, with respect to the positive side of the X axis, performing the following steps:

1. Click on the Dynamic Input icon in the status bar and it will turn blue when active. You can also type DYNMODE, then press Enter, and then type 3 and press Enter again to activate the Dynamic Input mode. The default value of the DYNMODE system variable is -3. You can also activate or deactivate the Dynamic Input mode using the F12 function key:

2. When the Dynamic Input mode is active, select the Line command and you will now notice a tooltip on the cursor with the value of the X and Y coordinates of the point, as in the following screenshot:

3. Now, click at a point in the drawing area and your tooltip on the cursor will change to represent a length and an angle field, as in the following screenshot:

4. Here, the length field is active and ready for your input. Type the length of the line in this field and press the Tab key on your keyboard.
5. The line will be locked at a length of 6 units and a lock sign will also appear next to the length field of the tooltip. Also, the angle field will be highlighted. Now, enter the angle value without any angle sign, which in this case will be 36, and press Enter.

We now have our required line with a length of 6 inclined to an angle of 36 degrees, with respect to the X axis.

So, as you have noticed, this is a quick and effective way of making geometries in a drawing, which you can use to bypass the coordinate or direct distance entry methods. If, for any reason, you don't want to use this Dynamic Input tool, then click on the Dynamic Input icon again on the status bar to deactivate it.

So, now you know that Dynamic Input makes it easy to add distances and angles, let's move on to learning about another status bar mode called ortho mode, which makes rendering horizontal and vertical lines a breeze. We will discuss this status bar mode in the next section.

So far, we have used the line command to make geometries in arbitrary directions. But if you want to restrict the direction of your lines to horizontal and vertical directions, then you can use ortho mode. Ortho mode restricts the movement of the cursor to a horizontal or vertical direction only, so with ortho mode active, you will be able to make lines only in a horizontal or vertical direction. To activate ortho mode, you can use the following workflow:

1. Click on the ortho mode icon in the status bar, as in the following screenshot, or press the F8 function key on your keyboard:

2. Select the Line tool from the Draw panel or use its command, L, and click on a point in the drawing area.
3. Now, move your cursor around and you will see that the line will remain restricted to a horizontal or vertical direction, depending on the movement of your cursor.

You can click on different points to make the geometry but the lines will always remain horizontal or vertical. To deactivate ortho mode, simply click on its icon in the status bar again or press the F8 function key on your keyboard. Just like ortho mode, there is another mode in the status bar that lets you make lines on any angle you specify. This mode is called polar tracking and we will discuss it in the next section.

Polar tracking allows you to make geometries at any angle you want. To activate polar tracking, click on its icon in the status bar, as in the following screenshot. You can also activate polar tracking by pressing the F10 function key on your keyboard:

When polar tracking is active, it will automatically deactivate ortho mode.

1. Start the Line command again by selecting its command, L
2. Click at a point in the drawing area and move your cursor in the horizontal or vertical direction.
3. You will notice a green tracking vector when the cursor is horizontal or vertical and this will help you to restrict the line to a horizontal and vertical direction:

But this is not all. In this case, you can assign a different angle to polar tracking mode and it will start restricting your lines to those angles.

1. To change the angle of polar tracking, click on the small arrow right beside the polar tracking icon.
2. When the angle menu shows up select the angle that you want to choose.
3. By default, 90 and its multiples will be selected, but we will change this to 30 and its multiples, as shown in the following screenshot:

4. You can select any other angle value as well, if you want to, from the list.

After making your selection, move your cursor again to the drawing area and now you will find a green tracking vector after an interval of every 30 degrees or at every angle that is a multiple of 30 degrees as shown in the following figure:

These status bar options allow you to make geometries. To make drawings, we will use a combination of these status bar tools as and when needed.

So, now that we know the methods for making simple line drawings with precision in AutoCAD, we will move on to learning about other geometries, such as circles, arcs, and polygons.

You can select the Circle command from the Draw panel in the Home tab, or you can also use its command, C. When you click the Circle flyout, you will find six different methods for making a circle in AutoCAD:

We will talk about all of these methods in the following sections.

The first option in the Circle flyout will let you make a circle with center and radius values. The following is the workflow for making a circle using a center and radius:

1. Select the first option from the Circle flyout. The command line will now prompt you to specify the center of the circle:

2. Click on any point in the drawing area and this will be selected as the center of the circle.
3. Now, the command line will prompt you to specify the radius of the circle. Type the radius value in the command line and press Enter to make the circle, or you can also move your cursor in the drawing area and click on a point to make your circle.
4. The circle will be made with a specified radius and center point.

Let’s repeat the preceding example again to make a circle with a diameter value this time:

1. Type C and press Enter to start the Circle command, or use the Circle tool from the Circle flyout.
2. Click on a point to specify the radius of the circle and then the command line will prompt you to specify its radius:

3. Don’t add the radius value at this point. In the command line, you will also see that after or, Diameter is highlighted with D in uppercase. Using this option, you can convert the radius input of the command line to the diameter. So, instead of radius, type D and then press Enter.

4. The command line will change again and this time it will prompt you to specify the diameter instead of the radius. You can also click on the highlighted Diameter option in the command line to select it instead of typing D and pressing the Enter key:

5. Now, type the value of the diameter in the command line and press Enter and your circle will be rendered with the required diameter. In the Circle flyout, the second option, Center, Diameter, will also let you make a circle with a center and diameter.

So, these two methods are nearly identical, the only difference being the radius or diameter value that you need to make the circle. The methods shown in the next section are, however, completely different and you don't even need the radius or diameter value for them.

The next circle option, 2-Point, requires you to specify two points for making the circle. For this, I will use the triangle shown here. Here, AB is 10 units and AC is 8 units in length:

In the following example, I will make a 2-point circle on the AC line of our sample triangle:

1. Select the 2-Point option from the Circle flyout.
2. Click on the A point, then click on the C point, and you will end up with a circle that looks like the one in the following diagram.
3. In this case, the AC line is on the diameter of the circle and the length of the AC line will be equal to the circle's diameter:

The next example, a 3-Point circle, will need three points to make the circle:

1. Select the 3-Point circle command from the Circle flyout and then click on the A point, then the B point, and finally, on the C point of our example triangle.
2. The circle will be made by connecting all three points of the triangle, as in the following diagram:

The next set of options in the Circle flyout will let you make the circle with the tangent and radius as references. We will discuss this next.

The next example will require you to specify two geometries on which the circle will be tangent and then the radius of the circle:

1. Select the Tan, Tan, Radius circle option from the flyout.
2. Click anywhere on the AB line and then click anywhere on the AC line. Now, the command line will prompt you to select the radius of the circle, as in the following screenshot.
3. Type 2 and press Enter and you will have your circle that is at a tangent to the AB and AC lines. The radius of the circle will be 2 units, as demonstrated in the following diagram:

In the last circle option, Tan, Tan, Tan, you need to only specify three geometries on which the circle will be tangent:

1. Select the Tan, Tan, Tan circle tool from the Circle flyout.
2. Click on the AB line, then click on the BC line, and finally, click on the AC line.

3. You will get a circle that is tangent to all three lines and it will look like this:

So, in this way, you can make circles using different methods and the selection of the method depends on the dimensions provided and the type of geometry you are required to make. In the next section, we will explore the arc tool, which is basically a part of the circle, but the workflow of making an arc is very different from that of a circle.

An arc is a segment of a circle and there are lots of ways that you can make one in AutoCAD. The method that you use to make the arc depends on the type of geometry that you want to make. In this case, I will explain some of the most frequently used methods of making an arc and I will use this right-angled triangle with the A, B, and C vertices in all of the following examples:

Select the Arc tool from the Draw panel in the Home tab. You can also use its command: ARC:

The command line will now prompt you to select the first point of the arc. Click on the A point of the triangle, then specify the second point as the B point, and the third point as the C point. An arc connecting the A, B, and C points will be formed, as shown:

This was the most basic and obvious way of making an arc in AutoCAD, but there are lots of other ways of making arcs as well. Let’s select the Start, Center, End option from the Arc dropdown and then, gradually, we will look at the other frequently used options.

As the name of the command suggests, you need to specify the start point first, then the center point, and lastly, the end point. Click on the B point to specify the start point, then click on the midpoint of the BC line, which will be taken as the center point of the arc, and lastly, click on the C point.

An arc that starts from the B point with the center on the midpoint of the BC line and ends on the C point will be formed, as shown:

In this case, the arc is formed outside the triangle because the arc will be formed in an anticlockwise direction with respect to the start point, which is the B point. If you select C as the start point and B as the end point, you will get your arc on the opposite side. Alternatively, you can also press and hold the Ctrl key while making the arc to change the direction of the arc, irrespective of the start and end points.

The next arc tool that I will tell you about is Start, End, Radius. For this arc tool, you need to specify the start point, end point, and radius value. The direction of the arc will be determined by the order in which you select the start and end points.

To make this arc, I will select the option from the Arc drop-down menu of the Draw panel and click on the B point, and then on the A point. Now, the command line will prompt you to specify the radius of the arc. Enter the radius value in the command line and press Enter. The final arc will look like this:

The diameter of the arc, in this case, should always be greater than the length of the AC line, otherwise it will not be possible to construct the arc. For our example, I have used a diameter of 16 units (or a radius of 8 units) and the length of the AC line is 14.

In this case, you too can change the order of the start and end points to reverse the direction of the arc, or you can press and hold the Ctrl key while making the arc to reverse the direction of the arc.

The last arc in this series of arc options that I will explain here is Center, Start, End. By now, you must have understood the workflow of making the arc. In this case, you need to click on the center point of the arc, then the start point, and lastly, the end point.

Select the tool from the Arc drop-down menu in the Draw panel and click on the midpoint of the AB line as the center point. Now, click on the A point and then click on the B point. The arc shown here will be made:

Here, we can also reverse the order of selection of the start and end points to reverse the direction of the arc. For example, you can select the midpoint of the AB line as the center of the arc, then B as the start point, and then A as the end point, and the arc will be formed inside the triangle. You can also press and hold the Ctrl key to reverse the direction of the arc while making it. In this case, the AB line will be the diameter of the arc.

So, these are the most frequently used arc tools from the list, but there are also other tools in the list and I encourage you to explore the remaining arc tools yourself. After arcs, we will explore the Rectangle command, which is another frequently used draw tool. You can make a rectangle or square using lines, but we have this direct tool as well, which enables us to make rectangles very easily with fewer clicks.

To make a rectangle, use the REC command or use the Rectangle tool from the Draw panel in the Home tab. The rectangle command will help you make a four-sided rectangle or square. There are a few different ways of making a rectangle using the rectangle tool. We will first learn how to make a rectangle using coordinates and later, we will also see the method of making a rectangle using Dynamic Input. Let's begin by using coordinates to make our rectangle.

To make a rectangle using coordinates, you need to deactivate the Dynamic Input option from the status bar. To turn it off, click on its icon in the status bar or press the F12 function key:

When Dynamic Input is on, a tooltip will show next to your cursor and when it is off, you won’t see a tooltip, as in the following screenshot:

Here, I will make a rectangle that starts from the origin and has a length of 8 units and a width of 3 units:

The following is the workflow for making this 8 x 3 rectangle:

1. Click on the Rectangle tool in the Draw panel or type the REC command and press Enter.
2. The command line will prompt you to specify the first point. Type 0,0 and press Enter.
3. Then, type 8,3 with the next prompt and press Enter again.
4. The final rectangle will be made with a length of 8 units and a width of 3 units.

In this case, the first point was the lower-left point of the rectangle, shown as 1 in the following diagram, which is also the origin, and the second point was the upper-right vertex with coordinates 8,3, shown as 2 in the diagram:

For point 2, we added 8,3, where 8 is the length as well as the X coordinate value and 3 is the height of the rectangle as well as the Y coordinate.

In the previous example, the rectangle started from the origin; hence, the coordinates of point 2 also represented the length and width. However, if you don’t want the rectangle to start from the origin and you instead want it to start from any other point, then you need to use the relative coordinates, which are explained here:

1. Start the Rectangle command from the Draw panel or use its REC command.
2. Click on any point in the drawing area to specify the first point of the rectangle.
3. Type @8,3 and press Enter to specify the next point of the rectangle.
4. The rectangle will be made with a length of 8 units and a width of 3 units.

In this case, we have used the @ sign before the point 2 coordinates because the first point was chosen randomly from the drawing area and it was not on the origin. So, adding the @ sign makes point 1 the origin for this particular case and the values of point 2 will be measured with respect to the first point.

If you start the Rectangle command from any random point and add the second point as 8,3, then the second point of the rectangle will end up on the absolute 8,3 point, with respect to the absolute coordinate system, and the length and width of the rectangle, in this case, won't be 8 and 3, respectively.

Using Dynamic Input skips all these issues that we have with coordinates and lets you directly add the length and width of the rectangle, so you will have your rectangle with those dimensions. Before we make a rectangle using the Dynamic Input status bar option, we need to first activate it:

1. Activate the Dynamic Input status bar option by clicking on its icon or using its function key, F12.
2. Start the Rectangle command from the Draw panel of the Home tab or use its REC command.

3. You will notice a tooltip next to your cursor with coordinate values in real time. Click on any point to specify the first point of the rectangle:

4. Type the length of the rectangle along the X axis and press the Tab key. The length of the rectangle will be locked to a 10 units length and the Y axis width field will become active:

5. Type the width value along the Y axis of the rectangle and press Enter again. In this case, I am using a width of 5 units.

The rectangle will be made with a length of 10 units and a width of 5 units. In this case, we used a positive value of X and Y that is, 10 and 5, but you can use negative values as well to make the rectangle in different quadrants with respect to the first point. For example, the -10 and 5 units will make the rectangle in the second quadrant, -10 and -5 will make it in the third, and 10 and -5 will make the rectangle in the fourth quadrant. The following illustration will clarify this point further:

The rectangle is a four-sided polygon but, in AutoCAD, you can make other polygons, such as a pentagon, hexagon, and heptagon as well. You can even make a polygon with tens or hundreds of sides. You can do all of this using the polygon command, which we will explore next.

Polygons are closed geometries made with three or more sides. The smallest polygon is a triangle and the largest polygon is a circle, which is made up of an infinite number of sides.

In AutoCAD, you can make a polygon with a minimum of 3 and a maximum of 1,024 sides:

The Polygon tool is in the Draw panel of the Home tab in the expanded rectangle flyout, as in the preceding screenshot. Before we start making a polygon, we need to learn about the two types of polygon options, namely inscribed, and circumscribed, in AutoCAD.

When you use the polygon command, you are presented with the inscribed and circumscribed options, so before we dig deeper into the polygon tool, let's understand what inscribed and circumscribed geometries are.

In the following diagram, the first polygon is inscribed in a circle with a radius equal to the length of the green line. In this case, the vertices of the polygon are touching the circumference of the circle.

In the second case, the polygon is circumscribed about the circle, which has a radius equal to the length of the green line and in this case, the midpoints of the sides of the polygon are touching the circumference of the circle:

When making polygons, AutoCAD will prompt you to specify the radius of the polygon, which is essentially the radius of the inscribed or circumscribed polygon. The type of polygon that you need to make depends on the dimensions provided in the drawing.

So, now that you know what an inscribed and a circumscribed polygon are, we are ready to make our first polygon. In this case, I will make a pentagon, which is a polygon with five sides, and I will use a polygon inscribed in a circle:

1. Select the Polygon tool from the Draw panel of the Home tab, or type POL and press Enter.
2. The command line will now prompt you to specify the number of sides of the polygon. Type 5 and press Enter.
3. Now, the command line will prompt you to specify the center of the circle. Click on a point in the drawing to specify the center.
4. Now, the command line will prompt you to specify the type of polygon: Inscribed in circle or Circumscribed about circle:

5. Select Inscribed in circle for this case.
6. Now, the command line will prompt you to specify the radius of the circle. Enter 5 as the radius and press the Enter key.

You will notice that an inscribed polygon with a radius of 5 units will be rendered. In this case, the radius of the polygon is the radius of the inscribed circle that this polygon is made in.

You can use a similar process to make a polygon that is circumscribed about the circle. Although these two options may seem like the only options for making a polygon in AutoCAD, its not always possible to have the radius of inscribed or circumscribed circles. If you only have the side length of the polygon, then you can use this next method to make a polygon using the side length.

In this example, I will make a hexagon with the length of its sides as 6 units:

1. Start the Polygon command from the Draw panel or use its POL command.
2. Now, the command line will prompt you to specify the number of sides. Type 6 and press Enter.
3. Now, the command line will prompt you to select the center of the polygon, but in this case, select the Edge option from the command line:

4. Now, specify the first point of the edge by clicking anywhere in the drawing area.
5. You will notice that the cursor will now follow the edge of your polygon. Simply click on the second point to make a polygon of a required length, or specify the length in the command line and press Enter:

A polygon with the required edge length will be made. In this case, you were not required to specify the inscribed or circumscribed circle as the reference.

Now that we know about some of the basic draw tools that make a drawing, let's move on to learning about a few of the basic modify tools.

To move drawings in AutoCAD, you can use the Move command from the Modify panel of the Home tab, or you can use its command, M:

In this case, we will use the Move tool to move the circle from one of the vertices of the triangle shown in the previous diagram down to the other:

1. Select the Move tool from the Modify panel and then click on the circle from the drawing area and press Enter.
2. Now, click on the center of the circle. This center will become the base point from where the circle will be picked.
3. Now, click on the lower-right vertex of the triangle. The circle will be moved to its new location.

To copy the circle on all three vertices, you can use the Copy tool from the Modify panel of the Home tab, or you can use its command, CO:

1. Click on the Copy command from the Modify panel and then click on the circle that you want to copy from the drawing area and press Enter.
2. Now, once again, click on the center of the circle and that will become the base point of your selection.
3. Click on the other two vertices of the triangle to paste the circle there.

To end the command, press Enter again. The final drawing after copying the circles on all three vertices will look like this:

So, now that you know about the basic drawing modification tools, such as Move and Copy, let's explore some other modification tools. We will discuss the Rotate tool next.

As the name suggests, the Rotate command can be used to rotate an object about a point. In this case, I will use a door symbol to explain the command, which is shown here:

The Rotate command rotates the selected object from its base point and you can rotate the object from its original angle or also by using a reference angle. In the following sections, we will discuss all the methods for using Rotate commands. Let's start with the simple rotate feature.

Currently, the door is horizontal and we can rotate it to change its rotation angle with respect to its current angle, which is 0 degrees, as the door is horizontal:

To rotate this door with respect to its original angle, we will perform the following steps:

1. Select the Rotate command from the Modify panel or use its command, ROTATE.
2. The command line will prompt you to select the objects. Click on the door to select it and press Enter.
3. Now, the command line will prompt you to specify the base point. Click on the lower-left corner of the door as the base point. The base point will become the pivot point of the rotation and it will remain fixed; the door will rotate about that point.
4. Now, the command line will prompt you to specify the angle of rotation. Type 30 and press Enter.

The door will rotate to an angle of 30 degrees, with respect to the current angle of 0 degrees, and the final door should look like this:

In a similar way, you can specify different base points and rotation angles to get different results. The Copy option, which shows up when you select the base point in the rotate command, will let you rotate a copy of the original drawing:

To use the Copy option, type C when the command line appears as in the previous screenshot and press Enter. This will select the Copy subcommand from the command line. You can also click on the highlighted Copy text from the command line to select this option.

Now, if you rotate the door, you will get a copy of the original door and the original door will also remain in its place. After using the Copy option in the preceding example, and a rotation angle of 90 degrees, we ended up with two doors that look like this:

When an object is at any known angle, it is easy to rotate it to any other angle, but if your object is at an unknown angle and you still want to rotate the object to any known final angle, then you can use Rotate with the Reference option, which we will discuss next.

In the previous case, the door symbol was at an angle of 0 degrees (perfectly horizontal) and hence, its rotation angle can be specified pretty easily. But let’s now take the case of this window symbol. It is inclined to an unknown angle and so, to rotate this to any specific angle, we will use the rotate with reference option:

Here, the window symbol is inclined to a random angle with respect to the horizontal axis. Now, if you want to rotate this window symbol so that it becomes perfectly horizontal, then you need to use the Reference subcommand of the Rotate command.

To do this, I will once again start with the Rotate command:

1. Type RO and press Enter to start the Rotate command or click its icon in the Modify panel of the Home tab.
2. Select all the objects that make the window and press Enter.
3. Click on the A point to specify the base point.
4. Select the Reference option from the command line, or type R and press Enter to select the Reference option.
5. Now, you need to specify the reference angle and in this case, we will specify it by clicking on A and then the B point.
6. Now, the command line will prompt you to specify the angle. Type 0 and press Enter.

You will notice that the window will now become horizontal; that is, its angle will now be 0 degrees, as in the following diagram:

In this case, by specifying the reference angle, you can make AutoCAD rotate the drawing to any specific angle with respect to the positive side of the X axis, even when the angle to which the object is inclined is unknown.

The next modify command that we will discuss is Fillet and this command lets you add rounded corners. It may look like a tool that can make subtle changes to the drawing, but you will find it pretty useful as it not only makes rounded edges, but it also has other sets of useful features, which we will discuss in the next section.

The Fillet command can be used to add round corners to the sharp edges of the drawing. For example, in this case, the fillets are added to the vertices of the A diagram, shown here, to make it look rounded in the corners, as shown in the B diagram:

To use the Fillet command, select it from the Modify panel in the Home tab, as in the following screenshot, or use its command, F:

Let’s take the example of the following diagram. This diagram has been made with the Line command:

Using the following steps, we will add a fillet to the A vertex of this diagram:

1. Select the Line command from the Modify panel or type F and press Enter to start the command.
2. Now, select the Radius option from the command line or type R and press Enter to select the radius option. Then, type the value of the radius that you want to apply on the vertex and press Enter.
3. Now, the command line will prompt you to select the objects to fillet.
4. Click on the AB line, then on the AE line, and the fillet will be applied to the A vertex and the final diagram will look like this:

You can also apply fillets on the open edges of the drawing. In the preceding example, the ED edge is open and we can close it with a rounded fillet or with a sharp vertex using the Fillet command:

1. Type F and press Enter to start the Fillet command or click on its icon on the Modify panel of the Home tab.
2. Click on the Radius option of the command line or type R and press Enter to start the option.
3. Type 0 and press Enter.
4. Click on the AE line, then the CD line.
5. The lines will merge at the point of intersection and you will get a closed drawing, as shown here:

In this case, you can also use a radius value at the ED vertex and then, instead of merging at a point, a fillet with a specified radius will be made.

While making the fillet, if you select the Polyline option from the command line, you can apply fillets on the multiple vertices of the drawing made with a polyline. As an example, if you want to apply a fillet on all four vertices of a rectangle with a length of 10 and a width of 5 units, then you can use this workflow:

1. Start the Fillet command from the Modify panel or using its command, F.
2. Type R to select the Radius option from the command line or click on the Radius option to select it.
3. Type 1 for the radius and press Enter.
4. Now, click on the Polyline option from the command line or type P and press Enter to select the option:

5. Click on any line segment of the rectangle and you will notice that the fillet will be applied to all four vertices of the rectangle.

So, now you know about the features of the fillet tool and how it can be used to add not only rounded corners but also other modifications to a drawing. Let's move on to the Modify command and explore one of the most frequently used modify tools, called Trim. This command lets you delete part of a drawing. We will explore its features in the next section.

Using the Trim command, you can remove parts of a drawing up to its intersection point or vertex. To explain this command properly, I will use the diagram shown here:

Here, we have three lines, A, B, and C, intersected by two arcs. We will trim the lines and arcs with respect to one another in the following examples:

1. Select the Trim command from the Modify panel or use its command, TR.
2. Hover your cursor over the A, B, or C lines on the right side of the red arc. You will notice that the color of the line will fade up to the red arc, indicating the part that will be trimmed.
3. Click the line and it will be trimmed up to the red arc.

In this case, if you click another line or arc, it will be trimmed up to the next available boundaries. This is the default way that the trim command works in the 2021 version of AutoCAD.

However, if you are using older versions of AutoCAD, then the workflow will be slightly different. Here is the trim command's workflow for the older versions of AutoCAD:

1. Select the Trim command from the Modify panel or use its command, TR.
2. Now, the command line will prompt you to select the objects. Click on the green arc and press Enter.
3. Now, click on the A, B, or C lines near the text and you will notice that the line will be trimmed up to the green arc, even though you have a red arc crossing the line before the green one.

In this case, you have selected the green arc as the boundary. So, it will trim the line with respect to the selected boundary only.

To include everything as a trimming boundary in older AutoCAD versions, select the Trim command again and press the Enter key directly, without making any specific selection from the drawing. The select all option is selected in the angle bracket and hence, pressing the Enter key selects all the objects in the drawing as trimming boundaries, as shown here:

This will select everything in the drawing area as a trimming boundary because the select all option is selected in the angle bracket, as in figure 2.66, and now if you click on any object, it will be trimmed up to the next boundary.

So, if you click on the A line somewhere near the A text, then the line will be trimmed up to the next boundary, which is the red arc, in this case. Selecting the same line again will trim it to the next boundary, which is a green arc, and so on. The last segment of the line will not be trimmed as there is no further trimming boundary.

Similar to the Trim tool, we have a tool that does the opposite of trim, that is, it will extend the object to the selected boundary. The workflow of the Extend tool is also similar to the Trim tool and we will discuss that in the next section.

The Extend command works in a completely opposite way. It extends the drawing up to the selected boundary. The workflow of the extend command is also the same and in this case, you also need a boundary that another geometry will extend to:

To explain the extend command, I will use this diagram shown in the preceding figure. Here, we will extend the lines up to the next boundaries using different extend options:

1. Type EX and press Enter, or click on the Extend tool from the Modify panel to start the extend command.
2. Simply click on the line you want to extend. In this example, click on the A line and it will extend up to the green arc.
3. Click on the A line again and it will again extend up to the red arc this time. If you click on the A line a third time, it will have no effect as there is no further boundary to extend the line.

This is the workflow for extending a command in the 2021 version of AutoCAD, but if you are using older versions of AutoCAD, the workflow once again will be slightly different. Here is the workflow of the Extend command from the older versions:

1. Type EX and press Enter or click on the Extend tool from the Modify panel to start the Extend command.
2. Now, the command line will prompt you to select the object to extend to. Click the red arc and press the Enter key.
3. Now, click on the A line and it will extend up to the red arc, ignoring the green arc that is before it.

If you want to include all the objects to be included as a boundary for the Extend command, then follow this workflow:

1. Start the Extend command again by using the EX command or click on the extend icon from the Modify panel of the Home tab.
2. When the command line prompts you to select the objects, press the Enter key without selecting anything. This will ensure all objects in the drawing area are selected as the extend boundary:

3. Now, click on the A line and it will extend to the green arc. Click on the A line again and it will extend further up to red arc.

Similarly, if you click on other lines, they will also extend up the first boundary, that is, the green arc, and then clicking on them again will extend it further to the red arc.

Let’s consider this situation where we have a boundary on both the sides of the AB line:

In this case, if you use Extend on the AB line, the line will extend either to the left or the right side to touch the circle. The side to which the line extends will depend on the point where you click on the line. If you click close to the A point, the line will extend to the left and similarly, if you click close to the B point, then the line will extend to the right. It's obviously not possible to click exactly at the center.

If you are not happy with the way the trim and extend commands work in the 2021 version of AutoCAD and want to switch back to the legacy behavior, then follow this workflow:

1. Select the Trim command from the Modify panel or use its command, TR.
2. Select the Mode option from the command line.
3. Change the option from Quick to Standard and you will have the standard behavior of the trim tool restored.

You can follow the same workflow for restoring the Extend command's behavior, too.

So, now we are equipped with the basic drawing tools that are required to make simple geometries in AutoCAD. I recommend you try making a simple drawing yourself with the tools learned about in this chapter.

In this chapter, we learned about different coordinate systems and input methods in AutoCAD. We also learned about the most basic draw command—Line—and different methods of making a line in AutoCAD. We then learned about other draw tools, such as Circle, Arc, Rectangle, and Polygon, which are the building blocks of drawings. Then, we also learned different methods of manipulating these drawing building blocks using modify commands, such as Move, Copy, Rotate, Fillet, Trim, and Extend.

These drawing and modifying tools are the building block of any AutoCAD drawing and you will find yourself using these tools in almost every drawing. In the next chapter, we will focus more on making complex drawings using advanced draw tools, status bar options such as object snap, and using modify tools such as offset, scale, and stretch. We will also discuss the hatch and gradient tools that let you fill closed boundaries with patterns and colors. So, I will see you in the next chapter.