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P,Q,B are collinear

Source: 2020 Korea National Olympiad P2

November 21, 2020
geometryPascal s theorem

Problem Statement

HH is the orthocenter of an acute triangle ABCABC, and let MM be the midpoint of BCBC. Suppose (AH)(AH) meets ABAB and ACAC at D,ED,E respectively. AHAH meets DEDE at PP, and the line through HH perpendicular to AHAH meets DMDM at QQ. Prove that P,Q,BP,Q,B are collinear.
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