2. Решить уравнение д) 2cos(4x/9 - π/2) - √2 = 0

2cos(4x/9 - π/2) = √2
cos(4x/9 - π/2) = √2/2
4x/9 - π/2 = ±π/4 + 2πn, n ∈ Z
4x/9 = π/2 ± π/4 + 2πn
4x/9 = 3π/4 + 2πn или 4x/9 = π/4 + 2πn
x = 27π/16 + 9πn/2 или x = 9π/16 + 9πn/2, n ∈ Z