# Thread: Integral of Function * sin / cos

1. ## Integral of Function * sin / cos

In your guys opinion, what is the best way to compute that kind of integral?

or

That integrals apperars when we´re calculating the coefficients of Fourier Series, and i guess there´s a "general" way to solve them.. Can someone help me?

Thanks!

[Im new here at this forum, im using FF3.0.9+GreaseMonkey+TexTheWorld to write in TeX here.]

2. Originally Posted by Tchelobh
In your guys opinion, what is the best way to compute that kind of integral?

or

That integrals apperars when we´re calculating the coefficients of Fourier Series, and i guess there´s a "general" way to solve them.. Can someone help me?

Thanks!

[Im new here at this forum, im using FF3.0.9+GreaseMonkey+TexTheWorld to write in TeX here.]
Usually you need to use integration by part.

3. Repeated Post =)

4. Hmm.. What im doing wrong?

let

So, we have

let ,so

and , so

So, computing , we got

Again, let , so

Computing again , then inserting the result in the above integral is the smartest way to calculate I ? =\

Am i doing something wrong?

Thanks