Cos (x) = - 1/5

sin (x) = - 1/5

tg (x) = - 1/5

ctg (x) = - 1/5

1) Cosx = - 1/5

x = + - arcCos (- 1/5) + 2 Пn, n э z

x = + - arcCos1/5 + 2 Пn, n э z

Sinx = - 1/5

2) x = (-1) ^n*arcSin (- 1/5) + Пn, n э z

x = (-1) ^ (n+1) * arcSin1/5 + Пn, n э z

3) tgx = - 1/5

x = arctg (- 1/5) + Пn, n э z

x = - arctg1/5 + Пn, n э z

4) ctgx = - 1/5

x = arcctg (- 1/5) + Пn, n э z

x = - arcctg1/5 + Пn, n э z