Parallel lines and planes in space: parallel

### 13.5.5 Parallel lines and planes in space: parallel

See section 12.7.5 for parallel lines in the plane.

The parallel command returns and draws a line or plane depending on the arguments. The possible arguments are:

- A point A and a line L.
  parallel(A,L) returns and draws the line through A parallel to L.
  Input:
  parallel(point(1,1,1),line(point(0,0,0),point(0,0,1)))
  Output:
- Two non-parallel lines L1 and L2.
  parallel(L1,L2) returns and draws the plane containing L2 that is parallel to L1.
  Input:
  parallel(line(point(1,0,0),point(0,1,0)),
  line(point(0,0,0),point(0,0,1)))
  Output:
- A point A and a plane P.
  parallel(A,P) returns and draws the plane through A that is parallel to A.
  Input:
  parallel(point(0,0,0),plane(point(1,0,0),point(0,1,0),point(0,0,1)))
  Output:
- A point A and two non-parallel lines L1 and L2.
  parallel(A,L1,L2) returns and draws the plane through A that is parallel to L1 and L2.
  Input:
  parallel(point(1,1,1),line(point(0,0,0),point(0,0,1)),
  line(point(1,0,0),point(0,1,0)))
  Output: