1-sinx=sinx 2cos2x=2.

1) 1 - sin x = Sin x
2Sin x = 1
Sin x = 1/2
x = (-1)^n arcSin 1/2 + n, nZ
x = (-1)^n /6 + n,nZ
2) 2 Cos x = 2
Cos x = 1
x = 2k , kZ
3) 5 - 5 Sin x = Cos2x
    5 - 5Sin x = 1 - 2Sin x
    2 Sin x -5Sin x +4 = 0
Sin x = t
2t - 5t +4 = 0
D = 1
t1= 3/2
t2 = 1
a) Sin x = 3/2
нет решений
б) Sin x = 1
     x = /2 + 2k , kZ