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Help with Volume...circular disk. 
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#1
Jan2208, 08:03 PM

P: 87

Consider the solid S described below.
The base of S is a circular disk with radius 3r. Parallel crosssections perpendicular to the base are squares. Find the volume V of this solid. I tried this.... A(x) = pi*r^2 = pi*(3r)^2 = pi*9r^2 V(x) = integral from 0 to 3r(pi*9r^2 dx) = pi*27r^3 Am I approaching this problem the wrong way? Thanks for the help! 


#2
Jan2208, 10:53 PM

HW Helper
P: 1,663

So what you need is to find the length of a chord of the circle which has its midpoint at a distance x from the circle's center. That length gives you the area A(x) of each crosssection. You would then integrate A(x) from x = 0 to x = 3r and multiply the resulting volume by 2. 


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