Question 37
TrigonometryIf 2 sin2 θ = 1 + Cos θ, 0° ≤ θ ≤ 90°, find the value of θ.
- A.90°
- B.60°
- C.45°
- D.30°
Show the answer and explanation
Answer: B (60°)
Explanation
2(1 − cos²θ) = 1 + cos θ gives 2cos²θ + cos θ − 1 = 0, (2cos θ − 1)(cos θ + 1) = 0. cos θ = ½, θ = 60°.