# math

If the area of a circle is increased by a factor of 9, the circumference of that circle will be increased by what factor?

a. 3
b. 6
c. 9
d. 18
e. 81

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2. 👎 0
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1. A = pi r^2

A' = 9 pi (r)^2 = pi R^2

so R^2/r^2 = 9
R/r = 3

so
THREE times

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posted by Damon

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