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March 29, 2015

March 29, 2015

Posted by **John** on Tuesday, August 19, 2014 at 10:06pm.

- Math -
**Reiny**, Tuesday, August 19, 2014 at 10:13pmoriginal radius --- r

new radius ------ r+1

original area = πr^2

new area = π(r+1)^2

π(r+1)^2 - πr^2 = 16π

divide by π and expand ...

r^2 + 2r + 1 - r^2 = 16

2r = 15

r = 7/5 units

check:

old area = π(7.5)^2 = 56.25π

new area = π(8.5)^2 = 72.25π

difference = 72.25P - 56.25π = 16π

all looks good!

- Math -
**John**, Tuesday, August 19, 2014 at 10:31pmAMAZING. Thanks Much.

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