MathDB
circumscribable quadrangles - ISL 1986

Source:

August 31, 2010
geometrycyclic quadrilateralcevian trianglecircumscribed quadrilateralIMO Shortlist

Problem Statement

Let AX,BY,CZAX,BY,CZ be three cevians concurrent at an interior point DD of a triangle ABCABC. Prove that if two of the quadrangles DYAZ,DZBX,DXCYDY AZ,DZBX,DXCY are circumscribable, so is the third.
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