I) 3cos (2x) - 3 = 0
3 cos (2x) = 3
cos (2x) = 1
2x = 2πn
x = πn, n∈Z
II) 4sin (3x) - 2 = -2
4sin (3x) = 0
sin (3x) = 0
3x = πk
x = πk/3, k ∈ Z
III) Переход от градусов к радианам по формуле
180° = π радиан
π/6 = 180°/6 = 30°
3π/4 = 3*180°/4 = 135°
18° = 180°/10 = π/10
90° = 180°/2 = π/2