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MathNet 2014 Question 86

Math Olympiad Vault · MathNet 2014

Question 86

Two tangents are drawn from a point $M$ to circle $k$, that touch it at points $G$ and $H$. If $O$ is the center of $k$ and $K$ is the orthocenter of the triangle $MGH$, prove that $\angle GMH = \angle OGK$.

Translation of the repeated Macedonian statement: Two tangents from $M$ touch circle $k$ at $G,H$. If $O$ is its center and $K$ is the orthocenter of triangle $MGH$, prove $\angle GMH=\angle OGK$.

Question illustration