cosП(x-1)/2=cos(+-П/4+2Пk)
П(x-1)/2=П/4+2Пk
(x-1)=1/2+4k
x=3/2+4k
П(x-1)/2=-П/4+2Пk
(x-1)=-1/2+4k
x=1/2+4k
cosП(x-1)/2=cos(+-П/4+2Пk)
П(x-1)/2=П/4+2Пk
(x-1)=1/2+4k
x=3/2+4k
П(x-1)/2=-П/4+2Пk
(x-1)=-1/2+4k
x=1/2+4k