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austrian midpoint, incircle and perpendiculars related

Source: 47th Austrian Mathematical Olympiad National Competition (Final Round, part 2, first day) May 25, 2016 p2

May 25, 2019
geometrymidpointincircleperpendicular

Problem Statement

Let ABCABC be a triangle. Its incircle meets the sides BC,CABC, CA and ABAB in the points D,ED, E and FF, respectively. Let PP denote the intersection point of EDED and the line perpendicular to EFEF and passing through FF, and similarly let QQ denote the intersection point of EFEF and the line perpendicular to EDED and passing through DD. Prove that BB is the mid-point of the segment PQPQ.
Proposed by Karl Czakler