CIRCLE command methods in AutoCAD - Step-by-Step Guide

Introduction

The CIRCLE command in AutoCAD helps you draw circles quickly using different methods. It solves the problem of creating precise round shapes by letting you choose how to define the circle's size and position.

When you want to draw a circle by specifying its center point and radius.

When you need to create a circle by defining its center and diameter.

When you want to draw a circle by selecting two points that define its diameter.

When you want to create a circle by specifying three points on its edge.

When you want to draw a circle tangent to two objects with a specific radius.

Steps

Step 1: Type CIRCLE and press Enter

- Command line

AutoCAD prompts you to specify the center point of the circle

💡 You can also click the Circle tool icon on the Draw panel

Step 2: Click to specify the center point or type coordinates

- Drawing area or command line

AutoCAD prompts you to specify the radius or diameter

💡 Use object snaps to pick exact points

Step 3: Type R for radius, D for diameter, 2P for two points, 3P for three points, or TTR for tangent-tangent-radius

- Command line

AutoCAD switches to the chosen method and prompts for required points or values

💡 Choose the method that fits your drawing needs

Step 4: Follow prompts to enter radius, diameter, or select points as needed

- Command line and drawing area

Circle is drawn on the canvas with specified size and position

💡 Use precise input for accurate circles

Before vs After

Before

No circle is present on the drawing area

After

A circle appears at the specified center with the chosen size and method

Settings Reference

Center Point

📍 Command line prompt after starting CIRCLE command

Defines the center location of the circle

Default: Click point

Radius or Diameter

📍 Command line prompt after center point

Defines the size of the circle

Default: Radius

Two Points (2P)

📍 Command line option during CIRCLE command

Draws circle by defining diameter endpoints

Default: Not default

Three Points (3P)

📍 Command line option during CIRCLE command

Draws circle passing through three points

Default: Not default

Tangent-Tangent-Radius (TTR)

📍 Command line option during CIRCLE command

Draws circle tangent to two objects with given radius

Default: Not default

Common Mistakes

Typing radius value without specifying R option

AutoCAD expects radius by default, but if you want diameter you must specify D

Type R and press Enter before entering radius value to be explicit

Clicking approximate points without object snaps

Circle may not align precisely with other objects

Use object snaps to select exact points for center or diameter

Using TTR method without selecting tangent objects

AutoCAD cannot create circle without tangent references

Select two objects to be tangent before entering radius

Summary

The CIRCLE command lets you draw circles using center-radius, center-diameter, two points, three points, or tangent methods.

You choose the method by typing options like R, D, 2P, 3P, or TTR during the command.

Use object snaps and precise input to create accurate circles.

Practice

1.

Which method of the CIRCLE command in AutoCAD allows you to draw a circle by specifying its center point and radius?

easy

A. 2 Points

B. 3 Points

C. Center, Radius

D. Tan, Tan, Radius

Solution

1. Step 1: Understand the Center, Radius method

   This method requires you to pick the center point of the circle and then enter the radius length.

2. Step 2: Compare with other methods

   Other methods use points on the circle or tangents, but only Center, Radius uses center and radius directly.

3. Final Answer:

   Center, Radius -> Option C

4. Quick Check:

   Center + radius = Center, Radius [OK]

Hint: Center and radius is the simplest circle method [OK]

Common Mistakes:

• Confusing 2 Points method with Center, Radius
• Thinking 3 Points method uses radius
• Mixing tangent methods with center-radius

2.

Which of the following is the correct syntax to start the CIRCLE command and draw a circle by specifying two points on its circumference?

easy

A. Type CIRCLE, then select 2 Points and pick two points on the circle

B. Type CIRCLE, then select 3 Points and pick three points on the circle

C. Type CIRCLE, then select Center and Radius

D. Type CIRCLE, then select Tan, Tan, Radius

Solution

1. Step 1: Recall the 2 Points method

   After typing CIRCLE, choosing 2 Points lets you pick two points on the circle's edge to define it.

2. Step 2: Verify other options

   Center and Radius needs center point and radius, 3 Points needs three points, Tan, Tan, Radius uses tangents.

3. Final Answer:

   Type CIRCLE, then select 2 Points and pick two points on the circle -> Option A

4. Quick Check:

   2 Points method = pick two points on circumference [OK]

Hint: 2 Points method needs exactly two points on circle edge [OK]

Common Mistakes:

• Selecting Center and Radius instead of 2 Points
• Confusing 3 Points with 2 Points method
• Using tangent method syntax incorrectly

3.

What will happen if you use the CIRCLE command with the 3 Points method and select three points that are collinear (all on a straight line)?

medium

A. AutoCAD will draw a circle passing through the three points

B. AutoCAD will show an error saying points are invalid

C. AutoCAD will draw a circle with zero radius

D. AutoCAD will draw a circle using only the first two points

Solution

1. Step 1: Understand 3 Points method requirements

   The 3 Points method requires three points that form a triangle to define a unique circle.

2. Step 2: Analyze collinear points case

   If points are collinear, no unique circle can pass through all three, so AutoCAD shows an error.

3. Final Answer:

   AutoCAD will show an error saying points are invalid -> Option B

4. Quick Check:

   Collinear points cause error in 3 Points method [OK]

Hint: 3 Points must not be in a straight line [OK]

Common Mistakes:

• Assuming circle draws with zero radius
• Thinking AutoCAD ignores third point
• Believing AutoCAD draws circle anyway

4.

You tried to draw a circle using the Tan, Tan, Radius method but AutoCAD gave an error. Which of the following is the most likely cause?

medium

A. You entered a radius smaller than zero

B. You used the 3 Points method instead

C. You did not specify the center point first

D. You selected only one tangent line instead of two

Solution

1. Step 1: Recall requirements for Tan, Tan, Radius

   This method needs two tangent objects and a positive radius value.

2. Step 2: Identify invalid radius input

   Entering a radius less than zero is invalid and causes an error in AutoCAD.

3. Final Answer:

   You entered a radius smaller than zero -> Option A

4. Quick Check:

   Radius must be positive in Tan, Tan, Radius method [OK]

Hint: Radius must be positive for tangent circle method [OK]

Common Mistakes:

• Selecting only one tangent instead of two
• Forgetting to pick center point (not needed here)
• Confusing method with 3 Points

5.

You need to draw a circle tangent to two existing lines and with a radius of 5 units. Which CIRCLE command method should you use, and what steps will you follow?

hard

A. Use 3 Points; pick three points on the circle edge

B. Use 2 Points; pick two points on the circle edge

C. Use Center, Radius; pick center then enter 5

D. Use Tan, Tan, Radius; select two tangent lines then enter 5

Solution

1. Step 1: Identify the requirement for tangency and radius

   Since the circle must be tangent to two lines and have a specific radius, the Tan, Tan, Radius method fits.

2. Step 2: Apply the Tan, Tan, Radius method

   Start the command, select the two tangent lines, then enter the radius of 5 units to draw the circle.

3. Final Answer:

   Use Tan, Tan, Radius; select two tangent lines then enter 5 -> Option D

4. Quick Check:

   Tangent lines + radius = Tan, Tan, Radius method [OK]

Hint: Use Tan, Tan, Radius for tangent lines and radius circle [OK]

Common Mistakes:

• Trying Center, Radius without knowing center
• Using 2 Points or 3 Points which ignore tangents
• Forgetting to select both tangent lines