- #1
supermiedos
- 63
- 0
Homework Statement
Find the volume between z = x^2 + y^2 and z = 3 - x - y
Homework Equations
None
The Attempt at a Solution
I must use a double integral. Using polar coordinates I find that the volume is equal to:
V = ∫∫(3 - rcosθ - rsinθ) r dr dθ - ∫∫r^2 r dr dθ
I'm struggling trying to find the region of integration.
I found that the projection onto the x-y plane is the circle x^2 + x + y^2 + y = 3, or (x+1/2)^2+(y+1/2)^2 = 7/2. By switching to polar coordinates I get: r^2 + rcos + rsinθ = 3
Since it's a circle, I assume that 0 ≤ θ ≤ 2∏.
But what about r?
I tought It went from 0 <= r <= √(7/2), but I'm not sure anymore since it's a circle centered outside the origin. What can I do?
Last edited: