Question

The circumference of a circle is 19pi ft. What is the area, in square feet? Express your

answer in terms of pi.

Answer 1

Explanation:

Circumference is found in

`C=2\pi r` while area is
`A=\pi r^2`

Since we know the circumference value, we can plug it in and solve for r:

Since
`C=2\pi r` and
`C=19\pi` , then

`19\pi=2\pi r` and

`(19\pi)/(2\pi)=r` The pi's cancel out, leaving us with the fact that

`r=(19)/(2)=9.5`

We will use that now in the area formula:

`A=\pi(9.5)^2` so

A = 90.25π

Answer 2

A = 90.25 pi ft^2

Explanation:

The circumference is given by

C = 2 * pi* r

19pi = 2 * pi * r

Divide each side by 2pi

19pi/2pi = 2 * pi *r/2pi

9.5 = r

Now find the area

A = pi r^2

A = pi ( 9.5)^2

A = 90.25 pi ft^2