2xin(x/2)cos(x/2)-3cos²(x/2)+3sin²(x/2)-2sin²(x/2)-2cos²(x/2)=0/cos²(x/2)
tg²(x/2)+2tg(x/2)-5=0
tg(x/2)=a
a²+2a-5=0
D=4+20=24
a1=(-2-2√6)/2=-1-√6⇒tg(x/2)=-1-√6⇒x/2=-arctg(1+√6)+πn,n∈z⇒
⇒x=-2arctg(1+√6)+2πn,n∈z
a2=√6-1⇒tg(x/2)=√6-1⇒x/2=arctg(√6-1)+πk,k∈z⇒x=2arctg(√6-1)+2πk,k∈z