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Standard angle chase

Source: Latvian TST for Baltic Way 2019 Problem 9

November 30, 2020
geometryrhombus

Problem Statement

Let ABCDABCD be a rhombus with the condition ∠ABC>90o\angle ABC > 90^o. The circle ΓB\Gamma_B with center at BB goes through CC, and the circle ΓC\Gamma_C with center at CC goes through BB. Denote by EE one of the intersection points of ΓB\Gamma_B and ΓC\Gamma_C. The line EDED intersects intersects ΓB\Gamma_B again at FF. Find the value of ∠AFB\angle AFB.
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