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Homework Statement
Hi, I have a problem with the following exercise.
Let C={(x,y,z)∈ℝ3 : x2+y2+z2≤1, z≥√(3x2+8y2)} be a subset of ℝ3. Calculate ∫∫∫C z dxdydz.
Homework Equations
Spherical coordinates, given by x=ρsinΦcosθ, y=ρsinΦsinθ, z=ρcosΦ, and cylindrical coordinates which are x=ρcosα, y=ρsinα, z=z
The Attempt at a Solution
The problem is that, starting from the set C I believe that √(3x2+8y2)≤z≤√(1-x2-y2) so that I should integrate the "∫zdz part" between these two extremes. But when it comes to the conditions on x and y I don't know how to proceed further. I tried to use spherical coordinates so that the first condition becomes ρ2≤1 but then the second one becomes cos(Φ)≥√(3sin2(Φ)cos2(θ)+8sin2(Φ)sin2(θ)) which is worse than the original condition. I also tried to use cylindrical coordinates so that even though the first condition does not improve much the second one becomes z2≥3ρ2cos2(α)+8ρ2sin2(α), which is better than the one I obtained using spherical coordinates, but even so I didn't go very far. Obviously there is some idea I am missing, what is in your opinion the best way to go on?
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