1) sinx = 1 - 2sin²x

2) √2 cos²7x - cos7x = 0

1) sinx=1-2sin^2x

2sin^2x + sinx - 1 = 0

D=в^2-4 ас=4+4+1=9=3

Sinx = - 1 или sinx = 1/2

x1=-П/2+2 Пn, n э Z

x2 = (-1) ^k * П/6 + Пk, k э Z

2) √2 cos²7x - cos7x = 0

cos7x (√2cos7x - 1) = 0

cos7x=0 или cos7x = √2 / 2

x1=П/14 + Пn/7, n э Z

x2 = + - п/28 + 2 Пn/7, n э Z

1) sinx=1-2sin^2x

2sin^2x + sinx - 1 = 0

D=9

Sinx = - 1 или sinx = 1/2

x=-П/2+2 Пn, n э Z x = (-1) ^k * П/6 + Пk, k э Z

2) √2 cos²7x - cos7x = 0

cos7x (√2cos7x - 1) = 0

cos7x=0 или cos7x = √2 / 2

x=П/14 + Пn/7, n э Z x = + - п/28 + 2 Пn/7, n э Z