Circles in space

### 27.9.1 Circles in space

See Section 26.10.1 for circles in the plane.

The circle command returns and draws a circle. It can take its arguments in two different ways.

1. Three points.
   - circle takes three arguments: A,B,C, three points.
   - circle(A,B,C) returns and draws the circle in plane ABC with a diameter AB.
2. Two points and a vector.
   - circle takes three points:
     - C, a point (which can be given by its coordinates).
     - v, a vector.
     - A, a point (which can be given by its coordinates).
   - circle(C,v,A) returns and draws the circle in plane C(C+v)C with center C and containing C+v.

#### Examples

circle(point(0,0,1),point(0,1,0),point(0,2,2))

circle(point(0,0,1),vector(0,1,0),point(0,2,2))