Помогите плиз с алгеброй!1!
cos(3x-п/4)=1/2

cos(3x - π/4) = 1/2

3x - π/4 = π/3 + 2πn
3x - π/4 = -π/3 + 2πn

3x = π/3 + 2πn + π/4
3x = -π/3 + 2πn + π/4

3x = 7π/12 + 2πn
3x = -π/12 + 2πn

x = 7π/36 + 2/3 * πn
x = -π/36 + 2/3 * πn

Ответ: -π/36 + 2πn/3; 7π/36 + 2πn; n ∈ Z