- #1

- 33

- 0

## Homework Statement

Find the integral of

[itex]\int\frac{cos(x)}{1+e^{x}}[/itex]

## Homework Equations

Given that

[itex]\frac{1}{1+e^{x}}[/itex]-[itex]\frac{1}{2}[/itex] is an odd function

## The Attempt at a Solution

I tried integration by parts, with both u = cos(x) and u = 1+e^x, and both only complicated it even more. I've not learned infinite series and sequences so I'm not sure thats the way.

I did try writing cos(x) as [itex]\frac{e^{ix}+e^{-ix}}{2}[/itex], but I'm not sure what to do after that. I can see that there'd be some hyperbolic stuff in here but again, I'm not sure where exactly to start.