In a right triangle, if angle K measures $20°$ and angle L measures $40°$, what is the measure of arc KL on the unit circle corresponding to angle K?

• A. $96°$
• B. $48°$
• C. $20°$
• D. $40°$

Answer: (C)

Verified step by step guidance

1. Identify the given angles in the right triangle: angle K = 20° and angle L = 40°. Since it's a right triangle, the third angle must be 90°.
2. Recall that on the unit circle, an arc corresponding to an angle at the center of the circle has a measure equal to that angle in degrees.
3. Understand that the measure of arc KL corresponding to angle K on the unit circle is simply the measure of angle K itself, because the arc subtended by an angle at the center equals the angle's measure.
4. Therefore, the measure of arc KL on the unit circle corresponding to angle K is 20°.
5. Summarize that the key concept is that the arc length in degrees on the unit circle directly corresponds to the central angle measure in degrees.