Ctg(x/2)-tg(x/2)-1-2ctgx=sin2x
cos(x/2)/sin(x/2)-sin(x/2)/cos(x/2) -1-2ctgx=sin2x
(cos²(x/2)-sin²9x/2))/(sib(x/2)cos(x/2)) -1-2ctgx=sin2x
2cosx/sinx -1-2ctgx=sin2x
2ctgx-1-2ctgx=sin2x
sin2x=-1
2x=-π/2+2πk
x=-π/4+πk,k∈z
-3π/2≤-π/4+πk≤0
-6≤-1+4k≤0
-5≤4k≤1
-5/4≤k≤1/4
k=-1 x=-π/4-π=-5π/4
k=0 x=-π/4