Q45
ArithmeticGeometry & Mensuration
The angle of elevation of a ladder leaning against a wall is 60° and the foot of the ladder is 4·7 m away from the wall. The length of the ladder is:
- a.4·7 m
- b.9·4 m
- c.8·4 m
- d.9·7 m
Answer: (B) 9·4 m
The ladder is the hypotenuse and the 4·7 m distance is adjacent to the 60° angle, so length = 4·7 ÷ $\cos 60^\circ$ = 4·7 ÷ $\frac{1}{2}$, i.e. the ladder is 9·4 m long. Option A, 4·7 m, is only the base distance.