Solve cos(θ)=−0.5\cos(\theta) = -0.5cos(θ)=−0.5 for θ∈[0,2π)\theta \in [0, 2\pi)θ∈[0,2π).
π3,2π3\frac{\pi}{3}, \frac{2\pi}{3}3π,32π
2π3,4π3\frac{2\pi}{3}, \frac{4\pi}{3}32π,34π
5π6,7π6\frac{5\pi}{6}, \frac{7\pi}{6}65π,67π
2π3,5π3\frac{2\pi}{3}, \frac{5\pi}{3}32π,35π