ISL 2011 G5
Let be a triangle with incenter and circumcircle . Let and be the second intersection points of with the lines and , respectively. The chord meets at a point , and at a point . Let be the intersection point of the line through parallel to and the line through parallel to . Suppose that the tangents to at and at meet at a point . Prove that the three lines , and are either parallel or concurrent.
Dataset text NuminaMath olympiads. Quoted with source.
Official text: IMO 2011 Shortlist booklet, page 9.
Solutions
Official solution Solution 1 by the IMO Problem Selection Committee
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