CIRCLE command methods in AutoCAD - Cheat Sheet & Quick Revision

Recall & Review

beginner

What is the CIRCLE command in AutoCAD used for?

The CIRCLE command is used to draw a circle by specifying its center point and radius or diameter.

beginner

Name two common methods to create a circle using the CIRCLE command.

You can create a circle by specifying the center and radius or by specifying the center and diameter.

intermediate

How do you draw a circle by specifying three points?

Use the 3-Point method: select three points on the drawing, and AutoCAD will create a circle passing through them.

advanced

What does the 'TTR' method stand for in the CIRCLE command?

TTR stands for Tangent, Tangent, Radius. It creates a circle tangent to two objects with a specified radius.

beginner

Explain the difference between specifying radius and diameter in the CIRCLE command.

Radius is the distance from the center to the edge of the circle. Diameter is twice the radius, the full width of the circle.

Which method requires you to pick three points on the drawing to create a circle?

A 3-Point

B TTR

C Center, Radius

D Center, Diameter

The 3-Point method creates a circle passing through three selected points.

What does the TTR method in the CIRCLE command do?

A Draws a circle by center and radius

B Draws a circle by center and diameter

C Draws a circle tangent to two objects with a given radius

D Draws a circle by three points

TTR stands for Tangent, Tangent, Radius, creating a circle tangent to two objects with specified radius.

If you specify the diameter instead of the radius, what changes?

A The circle size is twice as big

B The circle size is half

C The circle size stays the same

D The circle becomes an ellipse

Diameter is twice the radius, so specifying diameter doubles the size compared to radius.

Which of these is NOT a method to create a circle in AutoCAD?

A Center, Diameter

B Center, Circumference

C 3-Point

D Center, Radius

There is no 'Center, Circumference' method in AutoCAD's CIRCLE command.

What is the first step when using the Center, Radius method?

A Enter the diameter

B Select two tangent points

C Pick three points on the circle

D Specify the center point

You first specify the center point, then enter the radius.

Describe the different methods available in AutoCAD's CIRCLE command and when you might use each.

Think about how you define a circle's size or position in real life.

Explain how the TTR method works and why it might be useful in design.

Imagine fitting a round object exactly between two edges.

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