Maths Olympiad Prep

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Geometry Difficulty 5.3 AIME, harder Prove it Belarus

The point EE lies on the altitude BDBD of an acute triangle ABCABC. It is given that AED=50\angle AED = 50^\circ and the circumcircles of the triangles ADEADE and BECBEC tangent to each other at EE.
Find BCE\angle BCE.

Solution

4040^\circ.

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Source: MathNet, licensed CC-BY-4.0. Statement reproduced verbatim; metadata (topic, difficulty) added by this project.