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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.
Solution
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.
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