I need to find the circulation of F through L.
I tried to use Gauss' law to find it, so I first found the divergence and so on.
Anyway, somewhere in the solution I switch to polar coordinate system but I didn't changed z, what means I took the boundaries of z from r to 2-r^2 as you can see in the attach.
My question is, can I do that or do I need to change to spherical coordinate system? and if so, what are the boundaries of tetha?