Change to cartesian double integral to polar coordinates and evaluate

[Unemployed]

Homework Statement

integrate 1/((1+x^2+y^2)^2) dx dy Both x and y going from 0 to infinity

Homework Equations

x^2+y^2 =r

The Attempt at a Solution

After that I get 1/(1+r^2) ^2

Cannot visualize the function, do not know what the limits are.

If I could have any help it would be greatly appreciated

 

[Wingeer]

After the substitution you have:
$$\int_{0}^{\frac{\pi}{2}} \int_{0}^{\infty} \frac{1}{(1+r^2)^2} r dr d \theta$$
Imagine x and y both going from zero to infinity. They span the whole first quadrant and therefore theta goes from 0 to pi/2.
After this, try the substitution s=(1+r^2).