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, S1, S2, and S3,
are the areas of quadrilateral CGHM, triangle BEG, triangle DFM,
and quadrilateral AEHF, respectively, prove that S = S1+
S2 + S3.