The figure below shows a triangle ABC and a
triangle A1B1C1 so that A1A2, B1B2, and C1C2 are perpendicular
to BC, AC, and AB, respectively, and are concurrent at O1. If
AA3, BB3, and CC3, are perpendicular to B1C1, A1C1, and A1,B1,
respectively, prove that AA3, BB3, and CC3 are concurrent at O2.