Wednesday, 17 September 2014

trigonometry - Prove this formula for cosnthetacosnalpha


If n be any positive integer, prove that cosnθcosnα=2n1[cosθcosα][cosθcos(α+2πn)][cosθcos(α+(n1)2πn)]




I am struggling to establish this result. I have tried induction, but it doesn't help. Could I have a hint?

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