The figure below shows right
triangles ABC and A1B1C1 so that medians BM and B1M1 are
parallel. BA and B1A1 meet at D, BC and C1B1 meet at E, and C1A1
and AC meet at G. If F is on the extension of C1E, prove that angle ADA1 = angle CEF = half the
measure of angle CGC1.