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USAMO 2021 Problem 6

Let ABCDEFABCDEF be a convex hexagon satisfying AB‾∥DE‾\overline{AB} \parallel \overline{DE} , BC‾∥EF‾\overline{BC} \parallel \overline{EF} , CD‾∥FA‾\overline{CD} \parallel \overline{FA} , and AB⋅DE=BC⋅EF=CD⋅FA.AB \cdot DE = BC \cdot EF = CD \cdot FA. Let XX , YY , and ZZ be the midpoints of AD‾\overline{AD} , BE‾\overline{BE} , and CF‾\overline{CF} . Prove that the circumcenter of △ACE\triangle ACE , the circumcenter of △BDF\triangle BDF , and the orthocenter of △XYZ\triangle XYZ are collinear.

Dataset text AI-MO AoPS. Quoted with source.

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