cosx=-sqrt(3)/2
x=+-2/3П+2Пk
sqrt(2)cos2x=1
cos2x=sqrt(2)/2
2x=+-П/4+2Пk
x=+-П/8+Пk
сos(4x+П/8)=0
4x+П/8=П/2(2k+1)
4x=Пk+П/2-П/8=Пk+3П/8
х=Пk/4+3П/32
cos(x/2+П/3)=1
x/2+П/3=2Пk
x=4Пk+2П/3
cosx=-sqrt(3)/2
x=+-2/3П+2Пk
sqrt(2)cos2x=1
cos2x=sqrt(2)/2
2x=+-П/4+2Пk
x=+-П/8+Пk
сos(4x+П/8)=0
4x+П/8=П/2(2k+1)
4x=Пk+П/2-П/8=Пk+3П/8
х=Пk/4+3П/32
cos(x/2+П/3)=1
x/2+П/3=2Пk
x=4Пk+2П/3