MathDB
Elementary Geometry

Source: Bulgaria National Olympiad 2020

June 30, 2020
geometry

Problem Statement

On the sides of ABC\triangle{ABC} points P,QABP,Q \in{AB} (PP is between AA and QQ) and RBCR\in{BC} are chosen. The points MM and NN are defined as the intersection point of ARAR with the segments CPCP and CQCQ, respectively. If BC=BQBC=BQ, CP=APCP=AP, CR=CNCR=CN and BPC=CRA\angle{BPC}=\angle{CRA}, prove that MP+NQ=BRMP+NQ=BR.