What is the length of the hypotenuse of a 30-60-90 triangle if the side opposite the 60-degree angle is 6√3?

12√3
6
2√3
12

In a 30-60-90 triangle, the sides are in the ratio 1 : √3 : 2.

Since the side opposite the 60-degree angle is 6√3, the length of the hypotenuse (which is twice the length of this side) is 12√3.

Therefore, the correct answer is 12√3.