1
2sinycosy-2cos2ycosy-cosy=0
cosy*(2siny-2cos2y-1)=0
cosy=0⇒y=2πn,n∈z
2siny-2+4sin²y-1=0
4sin²y+2siny-3=0
siny=a
4a²+2a-3=0
D=4+48=52
a1=(-2-2√13)/8=-1/4-√13/4⇒sinx=-1/4-√13/4<-1 нет решения<br>a2=-1/4+√13/4⇒sinx=-1/4+√13/4⇒x=(-1)^k*arcsin(-1/4+√13/4)+πk,k∈z
2
x²-2x-3≥0
x1+x2=2 U x1*x2=-3
x1=-1 U x2=3
x∈(-∞;-1] U [3;∞)