MathDB
IMEO 2017 Problem 2

Source: IMEO

September 28, 2017
geometryJunior

Problem Statement

Let OO be the circumcenter of a triangleABC ABC. Let MM be the midpoint of AOAO. The BOBO and COCO intersect the altitude ADAD at points EE and FF,respectively. Let O1O1 andO2 O2 be the circumcenters of the triangle ABE and ACFACF, respectively. Prove that M lies on O1O2O1O2.