Question

The area of a circle is 81pi in.squared. What is the circumference, in inches? Express your answer in terms of pi

Answer 1

Answer:

18π

Step-by-step explanation:

the area of a circle is :

A= r²*π     where r is the radius

here r²  =81⇒ r= 9

the circumference of a circle is :

P= 2*r*π

P= 18π

Answer 2

Answer:

18 pi inches

Step-by-step explanation:

The area of a circle is given by

A = pi r^2

81 pi = pi r^2

Divide by pi

81 = r^2

Take the square root of each side

sqrt(81) = sqrt (r^2)

9 = r

We want the circumference

C = 2 * pi * r

C = 2 * pi * 9

C = 18 pi