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A bird is sitting on the top of a vertic...

A bird is sitting on the top of a vertical pole 20 m high and its elevation from a point O on the the ground is `45 ^(@).` If files off horizontally straight away from the point O. After one second, the elevation of the bird from O is reduced to `30^(@).` Then the speed (in m/s) of the bird is :

A

`40 (sqrt3-sqrt2)`

B

`20sqrt2`

C

`20 (sqrt3-1)`

D

`40 (sqrt2-1).`

Text Solution

Verified by Experts

The correct Answer is:
C
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Knowledge Check

  • The angle of clevation of the top Pof a vertical tower MP af heights from a point A in the horizontal plane is 45^(@) and from a point at a distance from Aom the line making an angle 30^(@) with AM, it is 60^(@), then:

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    C
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    D
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    C
    30 m
    D
    40 m

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