А) 2Sin x Cos x - 2Cos x = 0
Cos x(2Sin x - 2) = 0
Cos x = 0 или 2Sin x - 2 = 0
x = π/2 + πk, k∈Z Sin x = 1
x = π/2 + 2πn , n ∈Z
Б) 1 - 2Sin² x + 3Sin x = 1
-2Sin² x + Sin x = 0
Sin x( - Sin x + 1) = 0
Sin x = 0 или - Sin x +1 = 0
x = πn , n∈Z Sin x = 1
x = π/2 + 2πk , k ∈Z
В) 4Cos³x - 3Cos x= Cos² x
4Cos³ x - 3Cos x - Cos² x = 0
Cos x( 4Cos² x - 3 - Cos x) = 0
Cos x =0 или 4Cos² x - Cos x - 3 = 0
x = π/2 + πk , k ∈Z Решаем как квадратное
D = 49
Cos x = 1 Cos x = - 3/4
x = 2πn , n∈Z x = +- arcCos(-3/4) + 2πm,m∈Z