Answer:
4.7 yd
Explanation:
The horizontal lines in the diagram are parallel, so the angle of depression at D and the angle of elevation at F are congruent. So, you have a right triangle with the measure of one acute angle (F) and the length of the adjacent side (EF = 10 yd). You are being asked to find the opposite side (DE).
The mnemonic SOH CAH TOA reminds you of the necessary relation:
Tan = Opposite/Adjacent
Filling in the given information, you have ...
tan(25°) = DE/(10 yd)
Multiplying by 10 yd gives ...
(10 yd)tan(25°) = DE ≈ 4.663 yd ≈ 4.7 yd