2cos x - 1 ≥0
cosx>=0,5
(2-а)^2(2+а)^2=4-4а+а^2х4+4а+а^2=4-4а+4а^2+4а+а^2=4-5а^2
Вроде так)
=sin(2π+π/6)-cos(2π-π/6)+ctg(3π-π/4)=sinπ/6-cos(-π/6)+ctg(-π/4)=1/2-√3/2-1= -√3/2-1/2