MathDB
Spot the symmetry

Source: BdMO 2024 Higher Secondary National P5

March 18, 2024
geometryincirclehomothetyAngle Chasingexcircle

Problem Statement

Let II be the incenter of ABC\triangle ABC and PP be a point such that PIPI is perpendicular to BCBC and PAPA is parallel to BCBC. Let the line parallel to BCBC, which is tangent to the incircle of ABC\triangle ABC, intersect ABAB and ACAC at points QQ and RR respectively. Prove that BPQ=CPR\angle BPQ = \angle CPR.