13.7.10  The perpendicular bisector of a segment in the plane: perpen_bisector

See Section 14.6.2 for perpendicular bisectors in space.

The perpen_bisector command finds the perpendicular bisector of a line segment.

• perpen_bisector takes one argument:
  seg, a line segment (or the end points of the segment).
• perpen_bisector(seg) returns and draws the perpendicular bisector of seg.

Example.
Input:

or:

Output:

The perpen_bisector command can also take two lines as segments, in which case it returns and draws the perpendicular bisector of the segment from the first point defining the first line and the second point defining the second line.