Ω = {(x,y,z) ∈ R

^{3};

**x**;

^{2}+y^{2}+z^{2}≤1**x**;

^{2}+y^{2}≥1−z**x>0**;

**y>0**;

**z>0**}

With x>0 and y>0 I get θ∈(0,π/2).

My problem comes with the two first restrictions: I know x

^{2}+y

^{2}=r

^{2}, so I have:

- r
^{2}≤1-z^{2} - r
^{2}≥1-z

And from now on I don't know how to continue to resolve r.

Any help would be much appreciated.