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January 29, 2015

January 29, 2015

Posted by **Anonymous** on Sunday, November 18, 2007 at 12:43am.

Here is what I did: (unsure)

pi(r^2)=2pi(r)

r^2-r=0

r(r-2)=0

r=2

- calculus -
**Reiny**, Sunday, November 18, 2007 at 1:20amno, it is the rates of increase that are equal, so you have to set the derivatives equal.

dA/dr = 2pi(r)

dC/dr = 2pi

so 2pi(r) = 2 pi

r = 1

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