Prove: $\displaystyle sin (\frac{\pi }{25}) + sin (\frac{2\pi }{25}) +...+ sin (24\frac{\pi }{25})=cotg\frac{\pi }{25}$
Last edited by mr fantastic; Feb 26th 2011 at 12:59 PM. Reason: Re-titled.
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Originally Posted by arm Prove: $\displaystyle sin (\frac{\pi }{25}) + sin (\frac{2\pi }{25}) +...+ sin (24\frac{\pi }{25})=cotg\frac{\pi }{25}$ To get help you need to show some effort. Show your work and say where you're stuck.
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