SOLUTION: prove this equation to be an identity; (sin(3x/7))(cos(4x/7)) + (cos(3x/7))(sin(4x/7)) = sin(x)

Algebra ->  Trigonometry-basics -> SOLUTION: prove this equation to be an identity; (sin(3x/7))(cos(4x/7)) + (cos(3x/7))(sin(4x/7)) = sin(x)      Log On


   

Question 756970: prove this equation to be an identity;
(sin(3x/7))(cos(4x/7)) + (cos(3x/7))(sin(4x/7)) = sin(x)
Answer by tommyt3rd(5050) About Me  (Show Source):
You can put this solution on YOUR website!
Angle sum formula:
%0D%0Asin%28x%2By%29=sin%28x%29cos%28y%29-cos%28x%29sin%28y%29%0D%0A
the two angles are 3x/7 and 4x/7

therefore their sum is x



:)