MathDB
Paraguayan National Olympiad 2008, Level 3, Problem 4

Source:

August 31, 2014
geometryincenterAsymptote

Problem Statement

Let Γ\Gamma be a circumference and AA a point outside it. Let BB and CC be points in Γ\Gamma such that ABAB and ACAC are tangent to Γ\Gamma. Let PP be a point in Γ\Gamma. Let DD, EE and FF be points in BCBC, ACAC and ABAB respectively, such that PDBCPD \perp BC, PEACPE \perp AC, and PFABPF \perp AB. Show that PD2=PEPFPD^2 = PE \cdot PF