# Math Help - divergence and flux-angle issue

1. ## divergence and flux-angle issue

Hi,
I require i little bit of help. Please see below in green text to see my issue.thanks.

use the divergence theorem to find the outward flux of F=12yi+xyj-2zk across the boundary of the region D;the region inside the solid cylinder x^2+y^2≤4 between the plane z=0 and the paraboloid

for this question i Used ..∫∫∫divFdv

According to the solutions for this question
θ varies from 0 to 2pi..
why?
if z=0 there would only be half the cylinder..and hence half of 2pi=pi

Please explain why this is so??

2. ## Re: divergence and flux-angle issue

Hey n22.

The plane is perpendicular to the cylinder so you should get the full range of the cylinder cross section (0 to 2pi).