SOLUTION: cos(2x)=cos^2(x)-sin^2(x)

Algebra ->  Trigonometry-basics -> SOLUTION: cos(2x)=cos^2(x)-sin^2(x)      Log On


   

Question 1016544: cos(2x)=cos^2(x)-sin^2(x)
Answer by robertb(5830) About Me  (Show Source):
You can put this solution on YOUR website!
cos2x = cos(x + x) = cosx*cosx - sinx*sinx = cos^2(x) - sin^2(x), by a direct application of cosine of sum of angles.