Question

integrate then following function

Answer 1

\[\int\limits_{?}^{?}\sin4xcos5x dx\]

Answer 2

First, \[\sin\alpha\cos\beta=\frac{1}{2}[\sin(\alpha+\beta)+\sin(\alpha-\beta)].\]

Answer 3

ok but why did you use that identity

Answer 4

oh nvm i got it, what do you do after that