# Solid angle/cone

Hi everyone

I'd like to compute the solide angle defined by a cone whose angle θ is known.
I tried with the definition but I probably mistook since it lead me to compute an integral worth...0.
I then tried with a rule of three, but the result I get is clearly wrong too.

Could you explain me how to proceed?

$\int_0^{2\pi}\,\int_0^\theta\,sin\theta\,\mathrm{d}\theta\,\mathrm{d}\phi$