3-ctg²3x=0 помогите пожалуйста

3 - ctg²3x = 0; ctg²3x = 3;

ctg3x = √3;

3x = π/6 + πn, n∈Z; x = π/18 +πn/3, n∈Z.

ctg3x = -√3;

3x = 5π/6 + πn, n∈Z; x = 5π/18 +πn/3, n∈Z.