Problem 579: Quadrilateral, Diagonals, Triangles, Areas.
Level: Math Education, High School, SAT Prep, College
The figure shows a quadrilateral ABCD. The
diagonals AC and BD meet at O. If S1, S2, S3,
and S4
are the areas of triangles AOB, BOC, COD, and AOD, respectively, prove
that S1.S3 = S2.S4 .