Orthologic

Two Triangles $A_1B_1C_1$ and $A_2B_2C_2$ are orthologic if the perpendiculars from the Vertices $A_1$, $B_1$, $C_1$ on the sides $B_2C_2$, $A_2C_2$, and $A_2B_2$ pass through one point. This point is known as the orthology center of Triangle 1 with respect to Triangle 2.