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