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UI Post-UTME Mathematics 2021 (Model questions) Question 19

Question 19

Trigonometry

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

  1. A.40°
  2. B.60°
  3. C.69°
  4. D.32°
Show the answer and explanation

Answer: C (69°)

Explanation

x = 0.8660 − 0.5 = 0.366, so θ = cos⁻¹ 0.366 ≈ 68.5° ≈ 69°.