Final answer:
The cosine of 60 degrees is 1/2, and this is a common trigonometric value often memorized in relation to special angles.
Step-by-step explanation:
The value of cos60 degrees can be found using the unit circle or by memorizing common cosine values for special angles. For 60 degrees, the cosine value is ½, which means the correct answer is (a) 1/2. Therefore, among the provided options, the correct answer is (a) 1/2.