Let us have a denote the measure of the missing arc length. Since all circles measures 360°, it is then understood that all circles have an angle of 2π .
arc length = central angle 2π circumference
substitute values: a = 120° 2π 360° multiply them by 2π and cancel out 2π so you will have a = 24 π 36 Simplify 24/36 π--2/3π. Thus, the answer to this item is the third option.
