Ответ:
Пошаговое объяснение:
cos(3x + π/4) = - 1/2; 3x + π/4 = ± (π - arccos1/2) + 2πn, n ∈ Z; 3x = - π/4 ± (π - π/3) +2πn, n ∈ Z; 3x = - π/4 ± 2π/3 + 2πn, n ∈ Z, a) 3x₁ = - π/4 - 2π/3 + 2πn, n ∈ Z, 3x₁ = - 11π/12 + 2πn, n ∈ Z; x₁ = - 11π/36 + 2π/3 n, n ∈ Z; b) 3x₂ = - π/4 + 2π/3 + 2πn, n ∈ Z, 3x₂ = 5π/12 + 2πn, n ∈ Z, x₂ = 5π/36 + 2π/3n, n ∈ Z Ответ: x₁ = - 11π/36 + 2π/3 n, n ∈ Z; x₂ = 5π/36 + 2π/3n, n ∈ Z