The diameter of a circle is 18 kilometers. What is the length of a 120° arc?

Answer: 18.85 kilometers

Step-by-step explanation:

Arc length = 2πr∅°/360

= πr∅°/180°

Note, the diameter of the circle was given and not the radius.

Recall,

2r = d

r = d/2

= 18/2

= 9.

Now to find the length of the arc, use the formula above

Arc length = π x r x ∅°/180°

= 3.142 x 9 x 120°/180°

= 3,393.36/180°

= 18.85 kilometers.