Friday, July 6, 2018

trigonometry - Proof of a trigonometric identity

I need to prove that: 1+cos(a+b)cos(ab)=cos2(a)+cos2(b)


I tried to start from both ways but it always took me back to the same one again I tried also to prove that their - equal zero but I didn't work also

No comments:

Post a Comment

analysis - Injection, making bijection

I have injection f:AB and I want to get bijection. Can I just resting codomain to f(A)? I know that every function i...