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OMK 2010

Source: Malaysia National Olympiad 2010 Muda Category Problem 7

June 4, 2011
symmetrygeometrycircumcirclegeometry unsolved

Problem Statement

Let ABCABC be a triangle in which AB=ACAB=AC and let II be its incenter. It is known that BC=AB+AIBC=AB+AI. Let DD be a point on line BABA extended beyond AA such that AD=AIAD=AI. Prove that DAICDAIC is a cyclic quadrilateral.
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