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MathNet 2020 — Math Olympiad Vault — Part 01 Question 52

Math Olympiad Vault · MathNet 2020 — Math Olympiad Vault — Part 01

Question 52

Let $\triangle ABC$ be a triangle. On the sides $BC$, $CA$, $AB$ of the triangle, construct outwardly three squares with centres $O_a$, $O_b$, $O_c$ respectively. Let $\omega$ be the circumcircle of $\triangle O_aO_bO_c$.

Given that $A$ lies on $\omega$, prove that the centre of $\omega$ lies on the perimeter of $\triangle ABC$.