Question 15
(CUB 1) Prove that for all $n\in\mathbb N$ the following is true:
$$2^n\prod_{k=1}^n\sin\frac{k\pi}{2n+1}=\sqrt{2n+1}.$$
$$2^n\prod_{k=1}^n\sin\frac{k\pi}{2n+1}=\sqrt{2n+1}.$$
IMO 1973 — Shortlisted problems Question 15
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