- #1
BethW86
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Homework Statement
Hello, I am to find the volume of the solid given by x2 + (y-1)2=1 rotated about the y-axis. I may use either shells or cylindrical method. I attempted shell method, but am just learning this, still foggy and this is the one question that isn't coming out right.
Homework Equations
My understanding is that with shells, my rectangles are placed parallel to the rotation axis?
The Attempt at a Solution
I took the equation and solved for y, so that y=+- sqrt(1-x2)+1
I set up my integral as pi INT[-1,1] x(sqrt(1-x2)+1) dx
I'm not sure my integration is correct: pi [1/2sqrt91-x^2)x +x+1/2sin^-1(x)] |-1 to 1
When I did this, I got (pi^2)/4. The books says I should get (4pi)/3
Thanks so much for any direction. Feel free to use simple terms, I'm new at this :)