If an angle in standard position measures $120°$, what is the measure of its minor arc on the unit circle?

• A. $240°$
• B. $60°$
• C. $360°$
• D. $120°$

Answer: (D)

Verified step by step guidance

1. Recall that the minor arc corresponding to an angle in standard position on the unit circle is the smaller arc between the initial side and the terminal side of the angle.
2. Since the angle is given as 120° in standard position, this angle measures the arc from the positive x-axis counterclockwise to the terminal side.
3. The full circle measures 360°, so the major arc corresponding to this angle would be 360° - 120° = 240°.
4. The minor arc is the smaller of the two arcs formed, so it is the original angle measure itself, which is 120°.
5. Therefore, the measure of the minor arc on the unit circle corresponding to a 120° angle is 120°.