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MathNet 2021 — Part 10 Question 94

Math Olympiad Vault · MathNet 2021 — Part 10

Question 94

Let $ABC$ be a triangle with $AB = AC$ and $M$ is the midpoint of the altitude $AD$. Consider $(\omega)$ as the circle of center $M$ and tangent to $AB$, $AC$. From some point $T$ on the line $BC$ (outside triangle $ABC$), construct two tangents of $(\omega)$ and they cut $AB$ at $P$, $Q$, cut $AC$ at $R$, $S$. Prove that $PQ = RS$.