Find the circumference of the circle.
Formula: C = π d
Use 3.14 for pi.

Answer: I believe the answer is around/about 56.55
Step-by-step explanation: C=2πr=2·π·9≈ 56.54 or aound 56.52
Formula: C=2πr
Simplified Equation:
2 x 3.14 x 9= 56.52 - 56.55
Good luck!! I hope this helps! All you have to do is memorize the formula, break down & simplify the numbers and equation and you're golden!!
Edit: I reccomend checking out Khan Academy for math help!
Answer:
C= 56.52
Step-by-step explanation:
[tex]C=\pi d\\[/tex]
[tex]C=(3.14)(18)\\C=56.52[/tex]
If you didn't understand it in mathmatical terms, then here it is in English.
Step 1:
Re-write the formula (Please don't forget to do this step as it is a VERY important step in math)
Step 2:
Once yoou have re-writen the formula, substitute
In place of [tex]\pi[/tex] write "3.14"
In place of [tex]d[/tex] write 18. I got 18 because the diameter is 2r or twice the amount of the radius. So I added 9. So the equation would be [tex]C=(3.14)*(9+9)[/tex]
[tex]C=(3.14)*(18)[/tex]
Step 3:
Solve for "C" or Circumfrence
[tex]C=(3.14)*(18)\\C=56.52[/tex]
I hope it's clear and understandable. :D