The figure shows a parallelogram ABCD.
Lines BF and CF intersect DE at H and M, respectively. Lines BF
and CE meet at G. If S, S_{1}, S_{2}, and S_{3},
are the areas of quadrilateral CGHM, triangle BEG, triangle DFM,
and quadrilateral AEHF, respectively, prove that S = S_{1}+
S_{2} + S_{3}.
