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