Saturday, July 1, 2017

algebra precalculus - How to prove: $-frac{1}{sec2x}=frac{cos^3x-sin^3x}{cos x +sin x}+frac{cos2x}{(cos x +sin x)^2}$

How do you do it?
I'm really stuck on this proof. Can someone please explain? Thanks

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analysis - Injection, making bijection

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