Q. $cos\left(\frac{\pi}{11}\right)+cos\left(\frac{3\pi}{11}\right)+cos\left(\frac{5\pi}{11}\right)+cos\left(\frac{7\pi}{11}\right)+cos\left(\frac{9\pi}{11}\right)=$
Odisha JEEOdisha JEE 2010Trigonometric Functions
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