Using common unit-circle values, what is $cos60°$?

• A. $\frac{\sqrt{2}}{2}$
• B. $\frac{\sqrt{3}}{2}$
• C. $0$
• D. $\frac{1}{2}$

Answer: (D)

Verified step by step guidance

1. Recall that the cosine of an angle in the unit circle corresponds to the x-coordinate of the point where the terminal side of the angle intersects the unit circle.
2. Identify the angle given, which is 60 degrees, and remember the common special angles on the unit circle: 0°, 30°, 45°, 60°, and 90°.
3. Use the known unit circle values for cosine at 60°, which is derived from the coordinates of the point \( \left( \frac{1}{2}, \frac{\sqrt{3}}{2} \right) \) on the unit circle.
4. Recognize that the cosine value corresponds to the x-coordinate, so \( \cos 60^\circ = \frac{1}{2} \).
5. Compare this value with the given options to confirm that \( \frac{1}{2} \) is the correct cosine value for 60 degrees.