5. \( \cos(-305^\circ), \sin(\frac{17\pi}{4}), ctg 287^\circ, tg(-\frac{9\pi}{5}) \)

* \( \cos(-305^\circ) = \cos 305^\circ = \cos(360^\circ - 55^\circ) = \cos 55^\circ \) * \( \sin(\frac{17\pi}{4}) = \sin(4\pi + \frac{\pi}{4}) = \sin(\frac{\pi}{4}) \) * \( ctg 287^\circ = ctg(270^\circ + 17^\circ) = -tg 17^\circ \) * \( tg(-\frac{9\pi}{5}) = -tg(\frac{9\pi}{5}) = -tg(2\pi - \frac{\pi}{5}) = tg(\frac{\pi}{5}) \)