A building's rafter forms the hypotenuse of a 30°-60°-90° triangle with the roof's frame. If the rafter measures 9 feet, then the short leg measures feet.

In a 30°-60°-90° triangle, the hypotenuse is twice the length of the short leg. Since the rafter is the 9-foot hypotenuse, the short leg is 9 ÷ 2 = 4.5 feet. The correct choice is 4.5 feet.

AI-written and checked against the verified answer.