[tex] \int_{0}^{2 \lambda} \cos({\frac{kx}{2}}) \cos({nx}) dx[/tex](adsbygoogle = window.adsbygoogle || []).push({});

I can't find my calc2 notes and it's killing me! This thing came up half way through the computation of the fourier series of [tex]f(x) = A\cos({\frac{\pi x}{\lambda}})[/tex]..and i can't remember how to do it!

I am very aware of the trig identity below, but i would prefer not to use it for obvious reasons.

[tex]\cos{\alpha}\cos{\beta} = \frac{1}{2}[\cos{\frac{(\alpha + \beta)}{2} + \cos{\frac{(\alpha - \beta)}{2}][/tex]

I have the exact same question except instead of two cosines there's one cosine and one sine..any help is appreciated!

**Physics Forums | Science Articles, Homework Help, Discussion**

Join Physics Forums Today!

The friendliest, high quality science and math community on the planet! Everyone who loves science is here!

The friendliest, high quality science and math community on the planet! Everyone who loves science is here!

# Homework Help: How to integrate this? quick question

**Physics Forums | Science Articles, Homework Help, Discussion**