Question

What is the circumference of a circle with an area of 64 pi in^2?

a. 8 pi in
b. 16 pi in
c. 1024 pi in
d. 32 pi in
e. none of these

i got b. 16 pi in ?

Answer 1

@bibby

Answer 2

i also got 8 pi in but i thought 16 was correct

Answer 3

What is the radius of a circle with area 64 pi?

well first we need the formula for area

Answer 4

A=r^2

Answer 5

so we have \(A=\pi r^2\)
\(64\cancel{\pi}=\cancel{\pi} r^2 \)

Answer 6

okay and then circumference is 2 pi r

Answer 7

first, what is r?

Answer 8

i'm getting 28.3 as my answer

Answer 9

as the circumference

Answer 10

well not exactly

Answer 11

64=\(\ r^2\)
\(\sqrt{64}=\ r\)
r=8

Answer 12

and if i plug the formula in i'm getting 50.24?

Answer 13

2 *pi * r = 2*8*pi = 16pi

Answer 14

okay so 16 pi in is correct then?

Answer 15

yeah