Problem 353. Tangential quadrilateral, Diagonals, Incircles, Inradii.
Level: High School, College, SAT Prep.
The figure shows a tangential
quadrilateral ABCD. Diagonals AC and BD meet at E. If r1,
r2, r3, and r4, are the radii
of the incircles of triangles ABE, BCE, CDE, and ADE, prove that