Final answer:
To find the length of de, use the tangent function: de = 10 * tan(25°). The answer is c. 4.7 yd.
Step-by-step explanation:
To find the length of de, we can use the tangent function. The tangent of the angle of depression is equal to the opposite side (de) divided by the adjacent side (ef). Tan(25°) = de / 10. Rearranging the formula, we have de = 10 * tan(25°). Using a calculator, we find de ≈ 4.7 yards. Therefore, the answer is c. 4.7 yd.