MathDB
Equal radii lengths

Source: 239 2008 S2

July 28, 2020
geometry

Problem Statement

A circumscribed quadrilateral ABCDABCD is given. EE and FF are the intersection points of opposite sides of the ABCDABCD. It turned out that the radii of the inscribed circles of the triangles AEFAEF and CEFCEF are equal. Prove that AC⊥BDAC \bot BD.
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