MathDB
Surprisingly Easy Geo

Source: 2019 China Second Round P1

September 8, 2019
geometryChina second round

Problem Statement

In acute triangle ABC\triangle ABC, MM is the midpoint of segment BCBC. Point PP lies in the interior of ABC\triangle ABC such that APAP bisects BAC\angle BAC. Line MPMP intersects the circumcircles of ABP,ACP\triangle ABP,\triangle ACP at D,ED,E respectively. Prove that if DE=MPDE=MP, then BC=2BPBC=2BP.