2006 USAMO Problems/Problem 6

Revision as of 12:09, 12 July 2006 by Ragnarok23 (talk | contribs)


Let $ABCD$ be a quadrilateral, and let $E$ and $F$ be points on sides $AD$ and $BC$ respectively, such that $\frac{AE}{ED}=\frac{BF}{FC}.$ Ray $FE$ meets rays $BA$ and $CD$ at $S$ and $T$ respectively. Prove that the circumcircles of triangles $SAE, SBF, TCF,$ and $TDE$ pass through a common point.


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