excircle(Point1, Point2, Point3)
excircle(A,B,C) draws the A-excircle of the ABC triangle.
Draws one of the excircles of a triangle, a circle tangent to one side of the triangle and also tangent to the extensions of the other two sides.
excircle(GA, GB, GC) draws the circle tangent to BC and to the rays AB and AC.
excircle — Discussion