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JAMB Mathematics 1999 Question 24

Question 24

Trigonometry

A man 1.7m tall observes a bird on top of a tree at an angle of 30°. If the distance between the man's head and the bird is 25m, what is the height of the tree?

  1. A.26.7 m
  2. B.14.2m
  3. C.1.7 + 25√3/3 m
  4. D.1.7 + 25√2/2 m
Show the answer and explanation

Answer: B (14.2m)

Explanation

The 25 m line of sight is the hypotenuse, so the height above the man's eye is 25 sin 30° = 12.5 m. Adding his height: 12.5 + 1.7 = 14.2 m.