Answer:
Step-by-step explanation:
Remark
If you take one radius whose length is r and start it at (0,0) on one end and (r,0) at the other, and sweep it around so the (r,0) hits every point on the circumference of the circle, the radius will go through 360°.
You have only gone through 120°. That's no problem. All you have to do now is add a fraction that adjusts for the 120°.
Formula
Arc length = fraction * 2*pi * r
2*pi * r is the circumference
Arc Length = 2* (120/360) * pi * r
Givens
r = 13
pi = 3.14
Solution
Arc Length = (120/360) * 2 * pi * 13
Arc Length = 27.21
Answer
Arc Length = 27.21
