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MathNet 2018-part-04 — 181 problems (EN–VI) Question 113

Math Olympiad Vault · MathNet 2018-part-04 — 181 problems (EN–VI)

Question 113

Fix a circle $\Gamma$, a line $\ell$ tangent to $\Gamma$, and another circle $\Omega$ disjoint from $\ell$ such that $\Gamma$ and $\Omega$ lie on opposite sides of $\ell$. The tangents to $\Gamma$ from a variable point $X$ on $\Omega$ cross $\ell$ at $Y$ and $Z$. Prove that, as $X$ traces $\Omega$, the circle $XYZ$ is tangent to two fixed circles.