Tg(x/2)*2tg(x/2)/(1-tg²(x/2))=tg(x/2)+2tg(x/2)/(1-tg²(x/2))
tg(x/2)=a
2a²/(1-a²)=a+2a/(1-a²)
2a²/(1-a²)=(a-a³+2a)/(1-a³)
2a²/(1-a²)-(3a-a³)/(1-a²)=0
1-a²≠0⇒a≠1 U a≠-1
2a²-3a+a³=0
a(a²+2a-3)=0
a=0⇒tgx/2=0⇒x/2=πn⇒x=2πn,n∈z
a²+2a-3=0
a1+a2=-2 u a1*a2=-3
a=-3⇒tgx/2=-3⇒x/2=-arctg3+πn⇒x=-2arctg3+2πk,k∈z
a=1 не удов усл