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MathNet 2013 Question 77

Math Olympiad Vault · MathNet 2013

Question 77

In an acute triangle $ABC$ let the point of intersection of the altitude through $B$ and the angle bisector through $C$ be $D$. Let $E$ be the point symmetrical to point $D$ with respect to axis $AC$. Points $A$, $B$, $C$ and $E$ are concyclic. Prove that triangle $ABC$ is isosceles.