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WAEC Further Mathematics 2022 Question 30

Question 30

Trigonometry

Solve: 4sin2θ + 1 = 2, where 0° < θ < 180°.

  1. A.60°, 120°
  2. B.30°, 150°
  3. C.30°, 120°
  4. D.60°, 150°
Show the answer and explanation

Answer: B (30°, 150°)

Explanation

sin²θ = ¼, so sin θ = ½ (sin θ is positive in this range): θ = 30° or 150°.