Answer:
12.6 ft
Explanation:
Trig functions relate the sides and angles in a right triangle. Here, we're given an angle and an adjacent side, and we're asked to find the hypotenuse. The relevant trig relation is ...
Cos = Adjacent/Hypotenuse
cos(50°) = DE/CD = (8.1 ft)/CD
Solving for CD, we find ...
CD = (8.1 ft)/cos(50°) ≈ 12.601 ft
The length of CD is about 12.6 feet.