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MathNet 2016-part-02 — 184 problems (EN–VI) Question 79

Math Olympiad Vault · MathNet 2016-part-02 — 184 problems (EN–VI)

Question 79

Points $X$ and $Y$ are located on sides $AB$ and $AC$ of triangle $ABC$ ($X, Y \neq A$) such that the reflection of line $BC$ with respect to $XY$ is tangent to the circumcircle of triangle $AXY$. If $O$ denotes the circumcenter of triangle $ABC$, prove that the circumcircle of triangle $AXY$ is tangent to the circumcircle of triangle $BOC$.