\[1)\ ctg\ x > 4:\]
\[\pi n < x < arcctg\ 4 + \pi n.\]
\[2)\ tg\ x \leq 5:\]
\[- \frac{\pi}{2} + \pi n < x \leq arctg\ 5 + \pi n.\]
\[3)\ ctg\ x < - 4:\]
\[\pi - arcctg\ 4 + \pi n < x < \pi + \pi n\]
\[- arcctg\ 4 + \pi n < x < \pi n.\]
\[4)\ tg\ x \geq - 5:\]
\[- arctg\ 5 + \pi n \leq x < \frac{\pi}{2} + \pi n.\]