Решить уравнение: cos (x-p/4) = -1/2

cos(x - π/4) = -1/2x - π/4 = ±2π/3 + 2πn, n ∈ Zx = ±2π/3  + π/4 + 2πn, n ∈ ZОтвет: x = ±2π/3  + π/4 + 2πn, n ∈ Z.P.s.: arccos(-x) = π - arccosx