MathDB
PQ parallel RS

Source: Own. IMO 2022 Malaysian Training Camp 1

February 26, 2022
geometry

Problem Statement

Let ω\omega be the circumcircle of an actue triangle ABCABC and let HH be the feet of aliitude from AA to BCBC. Let MM and NN be the midpoints of the sides ACAC and ABAB. The lines BMBM and CNCN intersect each other at GG and intersect ω\omega at PP and QQ respectively. The circles (HMG)(HMG) and (HNG)(HNG) intersect the segments HPHP and HQHQ again at RR and SS respectively. Prove that PQRSPQ\parallel RS.