\[\lbrack 0;\ 3\pi\rbrack.\]
\[1)\ tg\ x = 3\]
\[x = arctg\ 3 + \pi n.\]
\[Ответ:\ \ arctg\ 3;\ arctg\ 3 + \pi;\ \]
\[\text{\ \ \ \ \ \ \ \ \ \ \ \ \ \ }arctg\ 3 + 2\pi.\]
\[2)\ ctg\ x = - 2\]
\[x = \pi - arcctg\ 2 + \pi n.\]
\[Ответ:\ - arcctg\ 2 + \pi;\ \]
\[- arcctg\ 2 + 2\pi;\ \]
\[- arcctg\ 2 + 3\pi.\]