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Celestor

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## Homework Statement

Given: y = sqrt(x), y=0, x=3

Find the volume of the solid bounded by these functions, revolved around B) y-axis and C) line x=3. (Disk method)

## Homework Equations

Disk method of finding volume using π ∫ r

^{2}dy

## The Attempt at a Solution

Ok so, the part of the problem that I am having trouble on is how to find the radius. I know that both integrals will be with respect to dy with the limits being 0 and sqrt(3) and I understand that these two integrals SHOULD be different, but I'm not sure what that difference is in terms of the radius in πr

^{2}.

Please refer to the solution to B and C given in this link (http://www.calcchat.com/book/Calculus-10e/7/2/11/). My question is, why is the radius [3

^{2}- (y

^{2})

^{2}] in B and why is the radius [3-y

^{2}]

^{2}in C. My problem is understanding why the power of 2 is distributed differently and how I'm supposed to interpret that based on the problem.

Thanks,