nπ±(−1)nπ6n \pi \pm(-1)^{n} \frac{\pi}{6}nπ±(−1)n6π
2nπ±π62 n \pi \pm \frac{\pi}{6}2nπ±6π
nπ±π6\mathrm{n} \pi \pm \frac{\pi}{6}nπ±6π