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WAEC Mathematics 1988 Question 8

Question 8

Trigonometry

If cos 60° = 1/2, which of the following angles has a cosine of 1/2?

  1. A.30°
  2. B.120°
  3. C.150°
  4. D.210°
  5. E.300°
Show the answer and explanation

Answer: E (300°)

Explanation

Cosine is positive in the first and fourth quadrants, so cos 300° = cos(360° − 60°) = cos 60° = 1/2.