Final answer:
In a right triangle with a hypotenuse of length 'a' and one angle measuring 60°, the length of the leg opposite the 60° angle is half the length of the hypotenuse (a/2).
Step-by-step explanation:
In a right triangle with a hypotenuse of length 'a' and one angle measuring 60°, the length of the leg opposite the 60° angle can be found using trigonometry. The side opposite the 60° angle is equal to half the length of the hypotenuse. Therefore, the correct answer is (a) a/2.