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JAMB Mathematics 2005 Question 34

Question 34

Trigonometry

If sin θ = −½ for 0 < θ < 360°, the value of θ is

  1. A.30° and 150°
  2. B.150° and 210°
  3. C.210° and 330°
  4. D.150° and 330°
Show the answer and explanation

Answer: C (210° and 330°)

Explanation

Sine is negative in the third and fourth quadrants. With reference angle 30°, θ = 180° + 30° = 210° or 360° − 30° = 330°.