Circumcircles of two vertices and the orthocenter
Channel: Saltire Software
Date: 2020-11-04

Let F be the orthocenter of triangle ABC.  Then the circumcenters of the four triangles ABF, ACF, FBC form a triangle congruent to ABC.  The sides are parallel.  We prove this using GXWeb, illustrating how the software can be used to gain geometric insight through algebra.