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MathNet 2009-part-05 — 172 problems (EN–VI) Question 8

Math Olympiad Vault · MathNet 2009-part-05 — 172 problems (EN–VI)

Question 8

Let $\triangle ABC$ be an equilateral triangle with height $13$, and let $O$ be its center. Point $X$ is chosen at random from all points inside $\triangle ABC$. Given that the circle of radius $1$ centered at $X$ lies entirely inside $\triangle ABC$, what is the probability that this circle contains $O$?