# Triple integral - solving issue

• Sep 29th 2011, 11:13 PM
Zrak
Triple integral - solving issue
Hello, I've got a problem which I am just stuck with..:

[Triple integral]D x^2+y^2 dxdydz, where D: 0<=x^2+y^2<=z^2 , 0<=z<=1

I have tried with spherical coordinates and other stuff(/tricks). I think my problem maybe is in dealing with the intervals. Could somebody please help me with at least some hints?

Sorry if there is something missing in my post. This is my first post on this forum. hehe

• Sep 30th 2011, 04:06 AM
tom@ballooncalculus
Re: Triple integral - solving issue
Are you clear that D is just a circular cone with a = 1 and h = 1? Cylindrical...

z is going...

from z = r (the side of the cone) up to z = 1 (the base)

... for every bit that r is going...

from zero (the z axis) along to as far as where r = z = 1

... for every bit that theta is going right round (zero to 2 pi).

And your integrand is r(x^2 + y^2) = r^3.
• Sep 30th 2011, 06:01 AM
HallsofIvy
Re: Triple integral - solving issue
Yes, cylindrical coordinates is the way to go.
• Sep 30th 2011, 11:58 AM
Zrak
Re: Triple integral - solving issue
Thank you! Solved it!