How to solve the following $$\iint\limits_{x^2+y^2\ge k}\frac{\exp(-(x^2+y^2)/2)}{2\pi}dxdy?$$
I think I should make the substitution $u=x^2+y^2$, but I don't know how the integral will look like.
How to solve the following $$\iint\limits_{x^2+y^2\ge k}\frac{\exp(-(x^2+y^2)/2)}{2\pi}dxdy?$$
I think I should make the substitution $u=x^2+y^2$, but I don't know how the integral will look like.