1. tg (20 пи/3) =

2. tg (28 пи/3) =

3. tg (-31 пи/6) =

4. ctg (16 пи/3) =

1. = tg (21π/3 - π/3) = tg (7π - π/3) = - tg (π/3) = - √3

2. = - tg (31π/6) = - tg (30π/6 + π/6) = - tg (5π + π/6) =

= - tg (π/6) = - 1/√3 = - √3/3

3. = ctg (15π/3 + π/3) = ctg (5π + π/3) = ctg (π/3) = 1/√3 = √3/3