Answer:
5/√3 inches long.
Explanation:
The property is that the lengths of the sides of a 30-60-90 triangle are in the ratio 1:2:√3. Thus if you know that the side opposite the 60 degree angle measures 5 inches then then this is √3 times as long as the side opposite the 30 degree so the side opposite the 30 degree angle is 5/√3 inches long.