Posted by **Thomas** on Sunday, January 5, 2014 at 4:55pm.

The area of circle c is 81 pi . if the radius of the circle is doubled, what is the circumference of the new circle ?

please answer and explain

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**Ms. Sue**, Sunday, January 5, 2014 at 4:57pm
162 pi

- math -
**Thomas**, Sunday, January 5, 2014 at 5:01pm
my answer is 162 pi too, but the answer is

a. 18 pi

b. 36 pi

c. 36 pi^2

d. 324 pi

e. 324 pi^2

- math -
**Steve**, Sunday, January 5, 2014 at 6:42pm
if a = 81pi, r = 9

if r = 18, c = 36pi

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