Answer:
θ = π/3 and 5π/3
Explanation:
f(x) = 2cos²θ
g(x) = -1 + 4cosθ - 2cos²θ
Since they intersect,
2cos²θ = -1 + 4cosθ + 2cos²θ
4cos²θ - 4cosθ + 1 = 0
(2cosθ - 1)² = 0
cosθ = 1/2
cosθ = π/3
At (0, 2π) interval,
θ = π/3 and 2π - π/3 = 5π/3
The correct option is the last one.