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Line Passing through Feet of Altitudes Intersects Circumcircle

Source: 2019 AIME II #15

March 22, 2019
AIMEAIME IIgeometrycircumcircle2019 AIME IIaltitudepower of a point

Problem Statement

In acute triangle ABCABC points PP and QQ are the feet of the perpendiculars from CC to AB\overline{AB} and from BB to AC\overline{AC}, respectively. Line PQPQ intersects the circumcircle of ABC\triangle ABC in two distinct points, XX and YY. Suppose XP=10XP=10, PQ=25PQ=25, and QY=15QY=15. The value of ABACAB\cdot AC can be written in the form mnm\sqrt n where mm and nn are positive integers, and nn is not divisible by the square of any prime. Find m+nm+n.