1+ cos4x = cos2x
1 + 2cos²2x -1 = cos2x
2cos²2x-cos2x=0
cos2x(2cos2x-1)=0
[cos2x=0
[cos2x=1/2
\\в объединение
[2x=π/2 + πn n∈Z
[2x=±π/3 + πk k∈Z
[x=π/4 + πn/2 n∈Z
[x=±π/6 + πk/2 k∈Z
4sin^2 x - 4sin x + 1 = 0Пусть sin x=t, |t|≤1
4t²-4t+1=0
(2t-1)²=0
t=1/2
sinx=1/2
[x=π/6 + 2πn n∈Z
[x=5π/6 + 2πk k∈Z