[tex]2cos^2x+sin4x=1[/tex]

cos2x+2six2xcos2x=0
cos2x(1+2sin2x)=0
cos2x=0
2x=П/2+Пk
x=П/4+Пk/2
1+2sin2x=0
sin2x=-1/2
x=(-1)^(k+1)п/12+пk/2