- #1
bugatti79
- 794
- 1
Homework Statement
Use Cauchy's Integral Theorem to evaluate the following integral
##\int_0^{\infty} \frac{x^2+1}{(x^2+9)^2} dx##
Homework Equations
Res ##f(z)_{z=z_0} = Res_{z=z_0} \frac{p(z)}{q(z)}=\frac{p(z_0)}{q'(z_0)}##
The Attempt at a Solution
I determine the roots of the denominator to be ##x=\pm 3i##.
How do I convert these into polar form. I know ##z=re^{i\theta}##
Do I need to convert these into ##z=e^{f(i\theta)}##?