Solve for θ\thetaθ: 2cos2(θ)−1=02\cos^2(\theta) - 1 = 02cos2(θ)−1=0 for 0≤θ<2π0 \leq \theta < 2\pi0≤θ<2π.
π4,3π4\frac{\pi}{4}, \frac{3\pi}{4}4π,43π
π4,3π4,5π4,7π4\frac{\pi}{4}, \frac{3\pi}{4}, \frac{5\pi}{4}, \frac{7\pi}{4}4π,43π,45π,47π
π3,5π3\frac{\pi}{3}, \frac{5\pi}{3}3π,35π
0,π0, \pi0,π