cos(x)=-1/5
sin(x)=-1/5
tg(x)=-1/5
ctg(x)=-1/5

1) Cosx = - 1/5
x = + - arcCos(- 1/5) + 2Пn, n э z
x = + - arcCos1/5 + 2Пn, 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