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Prove line tangent to circle given segment is bisected

Source: CSEMO 2018 Grade 10 Q3

July 30, 2018
geometry

Problem Statement

Let OO be the circumcenter of acute ABC\triangle ABC(AB<ACAB<AC), the angle bisector of BAC\angle BAC meets BCBC at TT and MM is the midpoint of ATAT. Point PP lies inside ABC\triangle ABC such that PBPCPB\perp PC. D,ED,E distinct from PP lies on the perpendicular to APAP through PP such that BD=BP,CE=CPBD=BP, CE=CP. If AOAO bisects segment DEDE, prove that AOAO is tangent to the circumcircle of AMP\triangle AMP.