The angle of elevation of a ladder leaning against a wall is 60º and the foot of the ladder is 4.6 m away from the wall. The length of the ladder is:

Answer: Option D

Let AB be the wall and BC be the ladder.

Then, ∠ACB = 60° = AC = 4.6m
$$\frac{AC}{BC}=\cos 60^{\circ }=\frac{1}{2}$$
⇒ BC = 2 × AC = 2 × 4.6 = 9.2m