Question

What is the radius of this circle of the circumference is 18pi cm?

Answer 1

`r=9`

Explanation:

The equation to find the circumference of a circle when given the radius is the following,

`C=r(\pi)(r)`

There (C) represents the circumference, (r) represents the radius, and (
`\pi`) represents the irrational numbers (3.1415...)

Substitute in the given values and backsolve for the radius,

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

Inverse operations,

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

`9=r`

Answer 2

r=9cm

Explanation:

C= 2pi r = 18 pi so

2r =18 so r = 18/2=9