Problem

Source: Argentina IMO TST Problem 5

Tags: geometry, cyclic quadrilateral, power of a point, radical axis, geometry unsolved, Harmonic Quadrilateral



Let $ ABC$ be a triangle, $ D$, $ E$ and $ F$ the points of tangency of the incircle with sides $ BC$, $ CA$, $ AB$ respectively. Let $ P$ be the second point of intersection of $ CF$ and the incircle. If $ ABPE$ is a cyclic quadrilateral prove that $ DP$ is parellel to $ AB$