Use the substitution $\displaystyle x=tan\theta$ to find the exact value of

$\displaystyle

\int{\frac{1-x^2}{1+x^2}}dx$

limits root 3 and 1

I know, that when you sub you have to change the limits:

$\displaystyle root 3=tan\theta$

$\displaystyle \theta=\frac{pi}{4}$

$\displaystyle 1=tan\theta$

$\displaystyle \theta=\frac{pi}{4}$

Please show me how to do this.

Thanks