most recent 30 from http://mathoverflow.net 2013-05-24T22:38:15Z http://mathoverflow.net/feeds/user/24674 http://www.creativecommons.org/licenses/by-nc/2.5/rdf http://mathoverflow.net/questions/100536/proof-of-gospers-sine-of-sum-of-n-angles-identity J Chu 2012-06-24T18:18:01Z 2012-06-24T18:18:01Z

<p>$sin(\sum_{k=1}^n x_k)=\frac{2^{n-1}}{n}\sum_{k=1}^n (-1)^{k-1} \prod_{j=1}^n sin(x_j-\frac{(k-j)\pi}{n})$ Gosper published very few papers about combinatory and hypergeometric sums, but none resource reveals the derivation of this sine identity. Any derivation hint/link help is appreciated!</p>