1)cos²x+6sinx-6=0
1-sin²x+6sinx-6=0
sin²x-6sinx+5=0
sinх=t
D=36-20=16=4²
t=(6±4)/2
t1=5;t2=1
sinx=5;x€∅
sinx=1; x=π/2+2πk;k€Z
2)cos2x=1+4cosx
2cos²x-1-1-4cosx=0
2cos²x-4cosx-2=0
cosx=t
t²-2t-1=0
D=4+4=8
t=(2±2√2)/2=1±√2
cosx=1+√2;x€∅
cosx=(1-√2)
x=±arccos(1-√2)+2πk;k€Z
3)sin(π-π/3)*cos(π-π/3)=
sinπ/3*(-cosπ/3)=
√3/2*(-1/2)=-√3/4
4)tg(-x)=-tgx