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USAMO 2025 Problem 4

  • Day 2

Let HH be the orthocenter of acute triangle ABCABC , let FF be the foot of the altitude from CC to ABAB , and let PP be the reflection of HH across BCBC . Suppose that the circumcircle of triangle AFPAFP intersects line BCBC at two distinct points XX and YY . Prove that CC is the midpoint of XYXY .

Dataset text AI-MO AoPS. Quoted with source.

Also USAJMO 2025 Problem 5.

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