SOLUTION: verify idenity (cos^4x – sin^4x)/(cosx + sinx) = cos x – sin x

Algebra ->  Trigonometry-basics -> SOLUTION: verify idenity (cos^4x – sin^4x)/(cosx + sinx) = cos x – sin x       Log On


   

Question 433311: verify idenity
(cos^4x – sin^4x)/(cosx + sinx) = cos x – sin x

Answer by belle3833(46) About Me  (Show Source):
You can put this solution on YOUR website!
%28cos%5E4%28x%29-sin%5E4%28x%29%29%2F%28cosx%2Bsinx%29
using difference of 2 squares
=
using difference of 2 squares again
=
cancelling out:
=%28%28cos%5E2%28x%29%2Bsin%5E2%28x%29%29%28cos%28x%29-sin%28x%29%29%29
%28cos%5E2%28x%29%2Bsin%5E2%28x%29%29=1+(identity)
so
=cosx-sinx
hope this helps