### 12.7.12 The exterior angle bisector: exbisector

The exbisector command takes as argument three points or a list of three
points.

exbisector returns the bisector of the exterior angle of the
triangle determined by the points; the first point is the vertex of
the angle, the opposite of the first and second points determine one
side of the angle and the first and third determine the second side.

Input:

exbisector(0,1,i)

Output: