1) cos2x -1 = sinx
cos²x - sin²x - sinx - 1 = 0
1-sin²x - sin²x - sinx - 1 = 0
-2sin²x - sinx = 0
2sin²x + sinx = 0
sinx(2sinx+1) = 0
1) sinx = 0
x = πn
2) 2sinx + 1 = 0
sinx = -1/2
x = (-1)^n+1 *π/6 + πn
2) sinx +√3cosx = 0
делим обе части на 2
sinx*1/2 + √3cosx*1/2 = 0
sin(x+π/3) = 0
(x+π/3) = πn
x = -π/3 + πn
3) cos2x = cosx-1
cos²x - sin²x - cosx + 1 = 0
cos²x -(1-cos²x) - cosx + 1 = 0
2cos²x - cosx = 0
cosx(2cosx - 1) = 0
1) cosx = 0
x = π/2 + πn
2) 2cosx - 1 = 0
cosx = 1/2
x = ±π/3 + 2πn