Possible Duplicate:
Help evaluating $\int \frac{dx}{(x^2 + a^2)^2}$
How to I begin this integration problem?
$\begin{align}\int_{0}^{1} \frac{dx}{{\left(x^2 + 1\right)}^{2}}\end{align}$
I'm not really sure how setup the triangle to do trigonometric substitution for this problem, since I am squaring the bottom, not taking the square root of it.
Could someone please demonstrate/explain how I could do this?
Thank you for your time.