Question

If the circumference of a circular region is 18 π cm, then what is its area?

A, 64 π 〖cm〗^2

B, 81 π 〖cm〗^2

C. 27 π 〖cm〗^2

D. 49 π 〖cm〗^2

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Answer 1

b

Explanation:

2pi r = 18pi

r= 9 pi

a= pi r square

= pi ×9 square

=81 pi cm square

Answer 2

`81\pi`

Answer B is correct

Explanation:

`c = 2\pi \: r \\ 18\pi = 2\pi \: r \\ (18\pi)/(2\pi) = r \\ raduis = 9`

`area = \pi {r}^(2) \\ \: \: \: \: \: \: \: \: \: \: \: \: \: \: = 9 * 9 * \pi \\ \: \: \: \: \: \: \: \: \: \: \: \: \: \: = 81\pi`