Question

A ladder 15 metres long just reaches the top of a vertical wall. If the ladder makes an angle of 60° with the wall, find the height of the wall.

Answer 1

Given that, the height of the ladder = 15 m

Let the height of the vertical wall = h

And the ladder makes an angle of elevation 60° with the wall i.e., θ = 60°

In ΔQPR,

cos 60° = `"PR"/"PQ" = "h"/15`

⇒ `1/2 = "h"/15`

⇒ h = `15/2`m

Hence, the required height of the wall `15/2`m.