Q. Use polar coordinates to find the volume of the given solid.bounded by the paraboloids z=12−x2−y2 and z=5x2+5y2
Convert to Polar Coordinates: Convert the equations of the paraboloids to polar coordinates.z=12−x2−y2 becomes z=12−r2.z=5x2+5y2 becomes z=5r2.
Find Intersection of Paraboloids: Find the intersection of the two paraboloids by setting their equations equal to each other.12−r2=5r2.Solve for r2.r2=612=2.Take the square root to find r.r=2.
Set Up Volume Integral: Set up the integral to find the volume. The volume V is the integral from 0 to 2π of the integral from 0 to 2 of (12−r2)−(5r2) times rdrdθ.
Simplify Integrand: Simplify the integrand.(12−r2)−(5r2)=12−6r2.Now multiply by r to get the integrand for the volume.12r−6r3.
Integrate with Respect to r: Integrate with respect to r from 0 to 2. The integral of 12r is 6r2. The integral of −6r3 is −1.5r4. Evaluate from 0 to 2.
Plug in Limits: Plug in the limits of integration.For r=2, we have 6∗(2)−1.5∗(22).For r=0, we have 0.Subtract the two results to get the volume for one slice.12−6=6.
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