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WAEC Mathematics 2016 Question 27

Question 27

Trigonometry

If cos θ = x and sin 60° = x + 0.5, 0° < θ < 90°, find, correct to the nearest degree, the value of θ.

  1. A.66°
  2. B.67°
  3. C.68°
  4. D.69°
Show the answer and explanation

Answer: D (69°)

Explanation

x = 0.8660 − 0.5 = 0.3660, so θ = cos⁻¹ 0.3660 ≈ 68.5°, which is 69° to the nearest degree.