RU-ALLRUSSIAN 1964 Problem 7
ABCD is a convex quadrilateral. A' is the foot of the perpendicular from A to the diagonal BD, B' is the foot of the perpendicular from B to the diagonal AC, and so on. Prove that A'B'C'D' is similar to ABCD.
Dataset text NuminaMath olympiads. Quoted with source.
Solutions
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