Exterior angle bisector

### 25.6.12 Exterior angle bisector

The exbisector command finds exterior angle bisectors.

- exbisector takes three arguments: a,b,c, three points (which can also be given as a list).
- exbisector(a,b,c) returns and draws the bisector of the exterior angle of the triangle determined by a,b and c; a is the vertex of the angle, the opposite of the ray through a and b determine one side of the angle and a and c determine the second side.