1) 2sinX = - 1

3) tg ( = - 1

1) 2sinX = - 1

sinx = - 1/2

x = (-1) ^n*arcsin (-1/2) + πn, n∈z

x = (-1) ^ (n+1) * arcsin (1/2) + πn, n∈z

x = (-1) ^ (n+1) * (π/6) + πn, n∈z

3) tg (π/2 - x) = - 1

ctgx = - 1

x = - π/4 = πk, k∈Z