Question

The area of a circle is 81л m². What is the circumference, in meters? Express your

answer in terms of π.

Answer 1

We can use the formula for the area of a circle to find the radius, and then use the formula for the circumference to find the answer.

A = pi * r^2

81pi = pi * r^2

r^2 = 81

r = 9

Now that we have the radius, we can use the formula for the circumference of a circle to find the answer.

C = 2 * pi * r

C = 2 * pi * 9

C = 18pi

Therefore, the circumference of the circle is 18pi meters.

Answer 2

Explanation:

Formulas:

A = (pi)(radius^2)

C = (pi)(Diameter)

Find the radius

81pi = pi * (r)^2

r^2 = 81

r = 9

Use radius to find diameter

D= 2r

D = 18

Use circumference formula

C = 18π