Prove that: {∑(r = 0 to n) nCr cos^(n - r) x sin ^(r) x}{∑(r = 0 to n) (-1)^(r) nCr cos^(n - r) x sin^(r) x} = cos ^(n) 2x NOTE: nCr is n choose r.
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Originally Posted by fardeen_gen Prove that: {∑(r = 0 to n) nCr cos^(n - r) x sin ^(r) x}{∑(r = 0 to n) (-1)^(r) nCr cos^(n - r) x sin^(r) x} = cos ^(n) 2x NOTE: nCr is n choose r. Remember that . Therefore, If you multiply them you get .
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