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A person, standing on the bank of a river, observes that the angle subtended by a tree on the opposite bank is `60^0dot` When he retreates 20m from the bank, he finds the angle to be `30^0dot` Find the height of the tree and the breadth of the river.

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Let `h` be the height of tree `PQ` and breadth of river `PS` be `x` ft.
Angle of elevation subtended by a tree is `600`.
Also, when he retreats `20` feet, the angle becomes `300`.
In triangle PQS, `tan 60 = h/x`
`=> sqrt (3) = h/x` ...
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RD SHARMA-SINE AND COSINE FORMULAE AND THEIR APPLICATIONS-Solved Examples And Exercises
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