(2n+1)π2(2 n+1) \frac{\pi}{2}(2n+1)2π
(4n+1)π2(4 n+1) \frac{\pi}{2}(4n+1)2π
nπ+π4n \pi+\frac{\pi}{4}nπ+4π
nπ+3π4n \pi+\frac{3 \pi}{4}nπ+43π