1. Для \(18^\circ\): \(\frac{18 \times \pi}{180} = \frac{\pi}{10}\) радиан.
2. Для \(150^\circ\): \(\frac{150 \times \pi}{180} = \frac{5\pi}{6}\) радиан.
3. Для \(-90^\circ\): \(\frac{-90 \times \pi}{180} = -\frac{\pi}{2}\) радиан.
Ответ: \(\frac{\pi}{10}\), \(\frac{5\pi}{6}\), \(-\frac{\pi}{2}\)