MathDB
St.Peterburg, P5 Grade 10, 2013

Source:

April 27, 2014
symmetrygeometry proposedgeometry

Problem Statement

Given quadrilateral ABCDABCD with AB=BC=CDAB=BC=CD. Let AC∩BD=OAC\cap BD=O, X,YX,Y are symmetry points of OO respect to midpoints of BCBC, ADAD, and ZZ is intersection point of lines, which perpendicular bisects of ACAC, BDBD. Prove that X,Y,ZX,Y,Z are collinear.
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