Произведение =0 когда множители =0
1) sinx/2=0
x/2=kπ, k∈Z
x=2kπ
2)cos²(2x+π/6)-3/4=0
cos²(2x+π/6)=3/4
2.1) cos(2x+π/6)=(√3)/2
2.2) cos(2x+π/6)=-(√3)/2
2.1) cos(2x+π/6)=(√3)/2
2.1.1)2x+6=arccos(√3)/2+2πn
2.1.2)2x+6=-arccos((√3/2)+2πn
2.1.1) 2x+6=arccos(√3)/2+2πn
2x+6=π/6+2πn
x=(π/6+2πn-6)/2
x=(π/12)+πn-3
2.1.2) x=-(π/12)+πn-3
2.2) cos(2x+π/6)=-(√3/2) arccos(-a)=π-arcos a
2.2.1) 2x+6=arccos(-√3/2)+2πn=π-accos((√/3)/2)+2πn=π-π/6+2πn
x=((5/6)π+2πn )/2=(5/12)π+πn
2.2.2) 2x+6=-arcos(-(√3)/2)+2πn
x=-5/12π+πn