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MathNet 2019-part-03 — 184 problems (EN–VI) Question 118

Math Olympiad Vault · MathNet 2019-part-03 — 184 problems (EN–VI)

Question 118

Let $\mathcal{P}$ be a simple polygon (non-self-intersecting) with perimeter $36$ that lies in a circle with radius $1$ and does not pass through its center. Prove that there is either a radius of this circle that intersects $\mathcal{P}$ at least $6$ times, or there is a second circle, concentric with this circle, that has at least $6$ common points with $\mathcal{P}$.