1+tg^2(x/2)>0
2*(1+tg^2(x/2))+(1-tg^2(x/2))=2tg(x/2)*(1+tg^2(x/2)
2+2tg^2(x/2)+1-tg^2(x/2)=2tg(x/2)+2tg^3(x/2)
2tg^3(x/2)-tg^2(x/2)+2tg(x/2)-3=0
2tg^3(x/2)-2 - (tg^2(x/2)-1)^2=0
2*(tg(x/2)-1)*(tg^2(x/2)+tg(x/2)+1) - (tg^2(x/2)-1)^2=0
(tg(x/2)-1)*(2tg^2(x/2)+2tg(x/2)+2-tg(x/2)+1)=0
tg(x/2)=1
(x/2)=(π/4)+πn, n ∈ Z
x= [b](π/2)+2πn, n ∈ Z[/b]
или
2tg^2(x/2)+2tg(x/2)+2-tg(x/2)+1=0
2tg^(2)(x/2)+(tg(x/2)+3=0
D < 0
нет корней
О т в е т. (π/2)+2πn, n ∈ Z