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WAEC Mathematics 1992 Question 35

Question 35

Trigonometry

A ladder leans against a vertical wall at an angle 60° to the wall. If the foot of the ladder is 5 metres away from the wall, calculate the length of the ladder.

  1. A.5√3/3 m
  2. B.5m
  3. C.10√3/3 m
  4. D.5√3m
  5. E.10m
Show the answer and explanation

Answer: C (10√3/3 m)

Explanation

The 5 m distance is opposite the 60° angle at the wall: sin 60° = 5/L, so L = 5 ÷ (√3/2) = 10/√3 = 10√3/3 m.