# Math Help - multiple integrals: cylinder

1. ## multiple integrals: cylinder

Could you please help me with this problems??? 1)Find the volume of solid bounded by planes x+y+z=6, z=0 and the cylinder= x^2+y^2=4
2)Find the volume of solid bounded by planes z=3x,z=0and the cylinder= x^2+y^2=1
I can't find the results when I put the polar coordinates

2. ## Re: multiple integrals: cylinder

Hint: In your triple integral in polar coordinates the limits on the z integral are 0 and 6-y-x, put the limits in polar form.

3. ## Re: multiple integrals: cylinder

i posted an image to show you how i started..i used double integrals alike this problem ..but probably this way is wrong..it would help me if you could tell me you opinion!!!

4. ## Re: multiple integrals: cylinder

Your question is exactly like the 1 in the video. But I think he goes about it in a more complicated way. Put the whole problem into polar coordinates and integrate with respect to z first.