Question

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

Answer 1

Answer:

$81\pi$

Answer B is correct

Step-by-step explanation:

$c = 2\pi \: r \\ 18\pi = 2\pi \: r \\ \frac{18\pi}{2\pi} = r \\ raduis = 9$

$area = \pi {r}^{2} \\ \: \: \: \: \: \: \: \: \: \: \: \: \: \: = 9 \times 9 \times \pi \\ \: \: \: \: \: \: \: \: \: \: \: \: \: \: = 81\pi$

Answer 2

Answer:

b

Step-by-step explanation:

2pi r = 18pi

r= 9 pi

a= pi r square

= pi ×9 square

=81 pi cm square