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Prove that two tangents intersect on BC

Source: Latvian TST for Baltic Way 2022 P11

November 25, 2022
geometrycircumcircle

Problem Statement

Let ABC\triangle ABC be an acute triangle. Point DD is arbitrarily chosen on the side BCBC. Let the circumcircle of the triangle ADB\triangle ADB intersect the segment ACAC at MM, and the circumcircle of the triangle ADC\triangle ADC intersect the segment ABAB at NN. Prove that the tangents of the circumcircle of the triangle AMN\triangle AMN at MM and NN intersect at a point that lies on the line BCBC.