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Archive for Tháng Mười Một, 2011

Circumscribed quadrilateral

This is a nice problem I found a long time ago. It’s easy but nice. You can solve it by using inversion.

Problem:  Given a circumscribed quadrilateral ABCD. AC intersects (ABD) and (CBD) again at E, F, respectively. Prove that FBED is also a circumscribed quadrilateral.

Link to problem above: http://www.artofproblemsolving.com/Forum/viewtopic.php?f=47&t=355881


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