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CMO 2025 Problem 4

  • Paper

Let ABCABC be a triangle with circumcircle Γ\Gamma and AB≠ACAB \neq AC . Let DD and EE lie on the arc BCBC of Γ\Gamma not containing AA such that ∠BAE=∠DAC\angle BAE = \angle DAC . Let the incenters of BAEBAE and CADCAD be XX and YY respectively, and let the external tangents of the incircles of BAEBAE and CADCAD intersect at ZZ . Prove that ZZ lies on the common chord of Γ\Gamma and the circumcircle of AXYAXY .

Dataset text NuminaMath olympiads. Quoted with source.

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