Answer: 0, π/3, 5π/3, 2π.
- A 0, π/3, 5π/3, 2π
- B 0, π/3, π
- C π/3, π, 5π/3
- D 0, 2π/3, 4π/3
Correct answer: A. 0, π/3, 5π/3, 2π
Explanation: Quadratic factoring: (2cosθ−1)(cosθ−1)=0. cosθ=1/2 → Q<sub>1</sub>: θ=π/3, Q4: θ=5π/3. cosθ=1 → θ=0 and θ=2π (boundary). All four solutions in [0,2π]: 0, π/3, 5π/3, 2π.
Unit circle with standard angles 0, 30, 45, 60, 90 degrees; at 45 degrees the point is (cos45, sin45) = (1/sqrt2, 1/sqrt2).
Concept context
Ratios, identities, and applications in triangles