- Thread starter
- #1

#### youth4ever

##### New member

- Feb 20, 2014

- 4

I have a complex integration problem:

The integral to calculate is :

**Integrate[Cos [mx]/(x^2 + a^2), {x, -Infinity, Infinity}]**

or if particularized for a=1, m=1 the integral will be :

**Integrate[Cos [x]/(x^2 + 1), {x, -Infinity, Infinity}]**

I know the answer for both of them:

**(Pi/a)*(e^-ma)**for the first

and

**Pi/e**for the second.

How this integral can be done through Complex integration ? I don't have a clue and I strongly wish to solve it.

Thanks.

PS: BTW, I would have written with math signs because I don't like the text style of writing math but I don't know how to do it here. Is there a trick ?