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A person standing on the bank of a river observes that the angle of elevation of the top of a tree on the opposite bank of the river is 60^ and when he retires 40 meter away from the tree the angle of elevation becomes 30^ . The breadth of the river is

Options

  1. A20 ~m
  2. B30 ~m
  3. C40 ~m
  4. D60 ~m

Correct answer

A. 20 ~m

Step-by-step solution

30^ = h 40+b 3 h=40+b 60^ =h / b h= 3 b b=20 m

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