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A ladder 15 m long just reaches the top ...

A ladder 15 m long just reaches the top of a vertical wall. If the ladder makes an angle of `60^0` with the wall, then the height of the wall is `15sqrt(3)m` (b) `(15sqrt(3))/2m` (c) `(15)/2m` (d) `15 m`

A

`6.5`m

B

`7.5`m

C

`8.5`m

D

`9.5`m

Text Solution

Verified by Experts

The correct Answer is:
B
Let PR be a ladder of length 15 m and QR, a wall of height h.
Given that `anglePRQ=60^(@)`
In `DeltaPQR`,
`cos60^(@)=h/(PR)rArr1/2=h/15`
`rArr h=15/2m`
`:." Height of the wall "=15/2m=7.5m`
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