olymmath

ISL 2015 G5

Let ABCA B C be a triangle with CA≠CBC A \neq C B. Let D,FD, F, and GG be the midpoints of the sides AB,ACA B, A C, and BCB C, respectively. A circle Γ\Gamma passing through CC and tangent to ABA B at DD meets the segments AFA F and BGB G at HH and II, respectively. The points H′H^{\prime} and I′I^{\prime} are symmetric to HH and II about FF and GG, respectively. The line H′I′H^{\prime} I^{\prime} meets CDC D and FGF G at QQ and MM, respectively. The line CMC M meets Γ\Gamma again at PP. Prove that CQ=QPC Q=Q P. (El Salvador)

Dataset text NuminaMath olympiads. Quoted with source.

Official text: IMO 2015 Shortlist booklet, page 7.

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).

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