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Reference

CIRCLE in AutoCAD

How AutoCAD's CIRCLE (C) works, prompt by prompt: centre and radius or Diameter, 2P, 3P and Ttr, a circle tangent to two objects. Try it free in your browser.

CIRCLE draws a circle from its centre and its radius, typed or given by a point on the circle, or in one of the other ways its first prompt offers. Enter at the radius repeats the last circle's size, kept for the drawing. While you give the radius, an amber dashed line runs from the centre to the cursor, past the rim when you give the diameter, as AutoCAD draws it. The circle lies in the plane of its first point, at the current elevation if the point has no Z of its own.

At the command line

The engine draws it and writes its history as you would type it: the prompts in AutoCAD 2027's order, with the same option letters.

Three circles: centre and radius, two ends of a diameter (2P), centre and Diameter.
  1. Command: CIRCLE
  2. Specify center point for circle or [3P/2P/Ttr (tan tan radius)]: 0,0
  3. Specify radius of circle or [Diameter]: 20
  4. Command: CIRCLE
  5. Specify center point for circle or [3P/2P/Ttr (tan tan radius)]: 2P
  6. Specify first end point of circle's diameter: 35,0
  7. Specify second end point of circle's diameter: 30,0
  8. Command: CIRCLE
  9. Specify center point for circle or [3P/2P/Ttr (tan tan radius)]: 100,0
  10. Specify radius of circle or [Diameter] <15.00>: D
  11. Specify diameter of circle <30.00>: 24
Three circles: centre and radius, two ends of a diameter (2P), centre and Diameter.

Options

3P

Through three points. Typed with Tangent snaps, _TAN at each, it is AutoCAD's Tan, Tan, Tan: the circle touching three objects.

2P

From the two ends of a diameter.

Ttr (tan tan radius) (T)

Tangent to two objects, with a radius: pick each line, circle or arc near where the circle should touch it, then give the radius. Of the circles that fit, it draws the one that touches nearest your picks; when none does, it says Circle does not exist..

Diameter (D)

At the radius prompt: give the diameter instead, typed or as a point.

What it does not do yet

Ttr on a polyline segment, which AutoCAD takes and MellowCAD refuses; the tool palette's Tan, Tan, Tan entry (typing it, 3P with three Tangent snaps, works); Quick Properties on a double-click of a circle.

What it does and still lacks, in detail (in English)

Questions

What is the shortcut for CIRCLE in AutoCAD?

C, then Enter or Space. The full name works too, and _CIRCLE in any language of AutoCAD.

How do I draw a circle tangent to two lines?

Choose Ttr, pick the first line, then the second, near where the circle should touch them, and type the radius.

How do I draw a circle tangent to three objects?

Choose 3P and type _TAN before each of the three points, picking each object near where the circle should touch it.

How do I draw a circle by its diameter?

Give the centre, then choose Diameter and type it. Or choose 2P and give the two ends of the diameter.

Related commands