Соедини части \cos t = 0 \cos t = -1 \sin t = 1 \sin t = 0 t=\dfrac{\pi}{2}+ 2\pi n, n \in \Z t=\pi n, n \in \Z t=\dfrac{\pi}{2}+ \pi n, n \in \Z t= \pi + 2\pi n, n \in \Z