# math

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

• math -

162 pi

• math -

a. 18 pi
b. 36 pi
c. 36 pi^2
d. 324 pi
e. 324 pi^2

• math -

if a = 81pi, r = 9
if r = 18, c = 36pi

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