The formula for finding the circumference of a circle is C = 2
r
It is fairly easy to find your answer using the information you have provided. All you need to do is substitute your radius into the formula I have provided above.
It'll look something like this: C = 2(3.14)(9)
Always remember that by using pi alone, you will get an answer that wouldn't be classified as correct. Use 3.14 instead.
C = 2(3.14)(9) = 56.66