MathDB
Intersections on intersections

Source: Baltic Way 2021, Problem 13

November 15, 2021
geometrygeometry proposed

Problem Statement

Let DD be the foot of the AA-altitude of an acute triangle ABCABC. The internal bisector of the angle DACDAC intersects BCBC at KK. Let LL be the projection of KK onto ACAC. Let MM be the intersection point of BLBL and ADAD. Let PP be the intersection point of MCMC and DLDL. Prove that PK⊥ABPK \perp AB.
Back to ProblemsView on AoPS