Номер 138 решите плз

1) cosx = 1/2 x = arccos(1/2) + 2πn, n ∈ Z x = π/3 + 2πn, n ∈ Z. 2) cosx = -√2/2 x = ±arccos(-√2/2) + 2πn, n ∈ Z. x = ±3π/4 + 2πn, n ∈ Z. 3) cosx = -√3/2 x = ±arccos(-√3/2) + 2πn, n ∈ Z x = ±5π/6 + 2πn, n ∈ Z. 4) cosx = √3/2 x = arccos(√3/2) + 2πn, n ∈ Z x = π/6 + 2πn, n ∈ Z. 5) cosx = -0,3 x = ±arccos(-0,3) + 3πn, n ∈ Z.