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WAEC Mathematics 1996 Question 40

Question 40

Trigonometry

If sin θ = cos θ, for 0° ≤ θ ≤ 360°, find the value of θ

  1. A.45°, 225°
  2. B.135°, 315°
  3. C.45°, 315°
  4. D.135°, 225°
  5. E.45°, 135°
Show the answer and explanation

Answer: A (45°, 225°)

Explanation

sin θ = cos θ means tan θ = 1. Tan is positive in the first and third quadrants, so θ = 45° or 180° + 45° = 225°.