SOLUTION: Simplify: cos^4 (x)-sin^4(x)/ cos^2(x)- sin^2(x)

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Question 187840: Simplify:
cos^4 (x)-sin^4(x)/ cos^2(x)- sin^2(x)
Answer by jim_thompson5910(35256) About Me  (Show Source):
You can put this solution on YOUR website!
... Start with the given expression.


Let y=cos%28x%29 and z=sin%28x%29


... Replace each "cos" with "y". Replace each "sin" with "z".


Factor the numerator (using the difference of squares formula).


Cancel out the common terms and simplify.


Plug in y=cos%28x%29 and z=sin%28x%29



... Use the identity to simplify.


So