ISL 2014 G7
Let be a triangle with circumcircle and incentre . Let the line passing through and perpendicular to intersect the segment and the not containing of at points and , respectively. Let the line passing through and parallel to intersect at , and let the line passing through and parallel to intersect at . Let and be the midpoints of and , respectively. Prove that if the points , and are collinear, then the points , and are also collinear.
Dataset text NuminaMath olympiads. Quoted with source.
Official text: IMO 2014 Shortlist booklet, page 9.
Solutions
Official solution Solution 1 by the IMO Problem Selection Committee
The terms of the source let olymmath link to this solution but not copy it. Read the solution (IMO official site).