MathDB

G4

Part of 2012 IMO Shortlist

Problems(1)

IMO Shortlist 2012, Geometry 4

Source: IMO Shortlist 2012, Geometry 4

7/29/2013
Let ABCABC be a triangle with AB≠ACAB \neq AC and circumcenter OO. The bisector of ∠BAC\angle BAC intersects BCBC at DD. Let EE be the reflection of DD with respect to the midpoint of BCBC. The lines through DD and EE perpendicular to BCBC intersect the lines AOAO and ADAD at XX and YY respectively. Prove that the quadrilateral BXCYBXCY is cyclic.
geometrycircumcircletrigonometryTriangleIMO Shortlist