(0,π2)\left(0, \frac{\pi}{2}\right)(0,2π)
(−π2,0)\left(-\frac{\pi}{2}, 0\right)(−2π,0)
[−π2,π2]\left[\frac{-\pi}{2}, \frac{\pi}{2}\right][2−π,2π]
(−π2,π2)\left(\frac{-\pi}{2}, \frac{\pi}{2}\right)(2−π,2π)