θ=nπ\theta=n \piθ=nπ
θ=(2n+1)π\theta=(2 n+1) \piθ=(2n+1)π
θ=(4n−1)π2\theta=(4 n-1) \frac{\pi}{2}θ=(4n−1)2π
θ=(4n+1)π2\theta=(4 n+1) \frac{\pi}{2}θ=(4n+1)2π