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MathNet 2020 — Math Olympiad Vault — Part 04 Question 85

Math Olympiad Vault · MathNet 2020 — Math Olympiad Vault — Part 04

Question 85

Given an inscribed pentagon $ABCDE$ with circumcircle $\Gamma$. Line $\ell$ passes through vertex $A$ and is tangent to $\Gamma$. Points $X, Y$ lie on $\ell$ so that $A$ lies between $X$ and $Y$. Circumcircle of triangle $\triangle XED$ intersects segment $AD$ at $Q$ and circumcircle of triangle $\triangle YBC$ intersects segment $AC$ at $P$. Lines $XE, YB$ intersect at $S$, and lines $XQ, YP$ at $Z$. Prove that circumcircle of triangles $\triangle XYZ$ and $\triangle BES$ are tangent.