Question

A ladder is placed in such a way that its foot is 15 m away from the wall and its top reaches a window 20 m above the ground. The length of the ladder is
(a) 35 m
(b) 25 m
(c) 18 m
(d) 17.5 m

Answer 1

Suppose BC is the ladder which is placed againts the wall OA. The foot of the ladder C is 15 m away from the foot O of the wall and its top reaches the window which is 20 m above the ground.


In right traingle BOC,
BC² = OC² + OB²
⇒ BC² = (15)² + (20)²
⇒ BC² = 225 + 400
⇒ BC² = 625
⇒ BC² = (25)²
⇒ BC = 25 m
Hence, the correct answer is option (b).