Question

The circumference of a circle is 18pi feet. What is the radius?

Answer 1

The circumference of a circle (C) is described by the formula:

`C=2\pi r`

Where r is the radius of the circle. We can solve for r in this equation to calculate its value, like this:

`\begin{gathered} C=2\pi r \\ (C)/(2\pi)=(2\pi r)/(2\pi) \\ (C)/(2\pi)=r*(2\pi)/(2\pi) \\ r=(C)/(2\pi) \end{gathered}`

Replacing the value of the circumference, we get:

`r=(18\pi)/(2\pi)=(18)/(2)=9`

Then, the radius of the circle is 9 feet