Find: $\displaystyle cos (\frac{2\pi }{9}). cos (\frac{4\pi }{9}). cos (\frac{8\pi }{9})$

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- Feb 26th 2011, 10:23 AMarmProduct of cosines.
Find: $\displaystyle cos (\frac{2\pi }{9}). cos (\frac{4\pi }{9}). cos (\frac{8\pi }{9})$

- Feb 26th 2011, 12:57 PMmr fantastic