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Bosnia and Herzegovina JBMO TST 2012 Problem 1

Source: Bosnia and Herzegovina Junior Balkan Mathematical Olympiad TST 2012

September 16, 2018
circlepentagongeometry

Problem Statement

On circle kk there are clockwise points AA, BB, CC, DD and EE such that ABE=BEC=ECD=45\angle ABE = \angle BEC = \angle ECD = 45^{\circ}. Prove that AB2+CE2=BE2+CD2AB^2 + CE^2 = BE^2 + CD^2