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Hexagon with a center of symmetry

Source: Poland Math Olympiad 1992 First Round #3

June 2, 2023
symmetry

Problem Statement

Given is a hexagon ABCDEFABCDEF with a center of symmetry. The lines ABAB and EFEF meet at the point AA', the lines BCBC and AFAF meet at the point BB', and the lines ABAB and CDCD meet at the point CC'. Prove that ABBCCD=AABBCCAB \cdot BC \cdot CD = AA' \cdot BB' \cdot CC'.