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JAMB Mathematics 1982 Question 25

Question 25

Angles and Polygons

A stone Q is tied to a point P vertically above Q by an inelastic string of length 2 metres. How high does the stone rise when the string is inclined at an angle 60° to the vertical?

  1. A.It does not rise
  2. B.2√3 metres
  3. C.3 metres
  4. D.1 metre
  5. E.√3 metres.
Show the answer and explanation

Answer: D (1 metre)

Explanation

The stone is now 2 cos 60° = 1m below P instead of 2m, so it has risen 2 − 1 = 1 metre.