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

math  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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