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JAMB Mathematics 2009 Question 35

Question 35

Trigonometry

A cliff on the bank of a river is 300 metres high. If the angle of depression of a point on the opposite side of the river is 60°, find the width of the river.

  1. A.100m
  2. B.75√3 m
  3. C.100√3 m
  4. D.200√3 m
Show the answer and explanation

Answer: C (100√3 m)

Explanation

The angle of elevation from the point is 60°, so width = 300/tan 60° = 300/√3 = 100√3 m.