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MathNet 2016-part-03 — 184 problems (EN–VI) Question 102

Math Olympiad Vault · MathNet 2016-part-03 — 184 problems (EN–VI)

Question 102

Let $ABC$ be a non-equilateral triangle such that $m(\angle A) = 60^\circ$. Let $D$ and $E$ be the intersection points of the Euler line of triangle $ABC$ and the sides of the angle $\angle BAC$. Prove that the triangle $ADE$ is equilateral.