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:  Choose the correct choice from the following.
A) 2.3 m	B) 4.6 m	C) 7.8 m	D) 9.2 m	E) 10.1

Rationale: "let ab be the wall and bc be the ladder . then , acb = 60 º and ac = 4.6 m . ac / bc = cos 60 º = 1 / 2 bc = 2 x ac = ( 2 x 4.6 ) m = 9.2 m . answer : option d"
Answer: D