Ответ:

1)

x+π/3=±arccos 1/2 + 2πk, k€Z

x=-π/3 ± π/3 + 2πk, k€Z

Ответ:

x=πk, k€Z

Объяснение:

2)

2cos²x - 3cosx + 1 = 0

cosx = t

2t² - 3t + 1 = 0

D = 9 - 8 = 1

t₁ = (3 - 1)/4 = 1/2

t₂ = (3 + 1)/4 = 1

1) cosx = 1/2

x = ± arccos(1/2) + 2πn, n ∈ Z

x = ± π/3 + 2πn, n ∈Z