13) √2 cos(2x - π/3) = 1
cos(2x - π/3) = 1/√2
2x - π/3 = ±arccos(1/√2) + 2πn, n ∈ Z
2x - π/3 = ±π/4 + 2πn, n ∈ Z
2x = π/3 ± π/4 + 2πn, n ∈ Z
x = π/6 ± π/8 + πn, n ∈ Z
x = (4π ± 3π)/24 + πn, n ∈ Z
x₁ = 7π/24 + πn, n ∈ Z
x₂ = π/24 + πn, n ∈ Z
Ответ: x₁ = 7π/24 + πn, n ∈ Z; x₂ = π/24 + πn, n ∈ Z