SOLUTION: Use a product-to-sum formula to rewrite sin4d cos as a sum or difference. sin4d cosd =

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Question 1070185: Use a product-to-sum formula to rewrite sin4d cos as a sum or difference.
sin4d cosd =
Answer by Edwin McCravy(20060) About Me  (Show Source):
You can put this solution on YOUR website!
Adding the formulas



we get

sin%28A%2BB%29%2Bsin%28A-B%29%22%22=%22%222sin%28A%29cos%28B%29

or 

expr%281%2F2%29%28sin%28A%2BB%29%2Bsin%28A-B%29%5E%22%22%29%22%22=%22%22sin%28A%29cos%28B%29

or the product-to-sum formula:

sin%28A%29cos%28B%29%22%22=%22%22expr%281%2F2%29%28sin%28A%2BB%29%2Bsin%28A-B%29%5E%22%22%29

Substituting A = 4d, B = d

sin%284d%29cos%28d%29%22%22=%22%22expr%281%2F2%29%28sin%284d%2Bd%29%2Bsin%284d-d%29%5E%22%22%29%22%22=%22%22expr%281%2F2%29%28sin%285d%29%2Bsin%283d%29%5E%22%22%29

Edwin