Answer :

TSO
There are 2 formula to find the circumference of a circle.

[tex]\huge{\boxed{\bf{Circumference=2\pi r}}}[/tex]

[tex]\huge{\boxed{\bf{Circumference=\pi D}}}[/tex]

[tex]\pi[/tex] is approximately 3.14
r is radius
D is diameter

and just a side note, [tex]\huge{\boxed{\bf{2 r = D}}}[/tex]
Hope that formula helps you :)

Answer:

2rPi:

Step-by-step explanation:

You can multiply the radius by 2, which gives you the diameter. Then you multiply by Pi, which is 3.14 OR 22/7. If you are in Khan Academy, don't use 22/7.