Cos2x=1-cos(пи ** 2-x)

Question

Cos2x=1-cos(пи на 2-x)

Answer 1

Cos(pi/2 - x) = sin x
cos 2x = 1 - 2sin^2 x
Подставляем
1 - 2sin^2 x = 1 - sin x
0 = 2sin^2 x - sin x
sin x*(2sin x - 1) = 0
1) sin x = 0; x1 = pi*k
2) sin x = 1/2; x2 = pi/6 + 2pi*k; x3 = 5pi/6 + 2pi*k