V3sin 2x+3cos 2x=0 (:cos 2x)
V3tg 2x+3=0
V3 tg 2x=-3
tg 2x=-3/V3
tg 2x=-V3
2x=-П/3+Пк;к€Z
X=-П/6+Пк/2;к€Z
3П/2<=-П/6+Пк<=3П
3П/2+П/6<=Пк<=3П+П/6
10П/6<=Пк<=19П/6
10/6<=к<=19/6
К=2;3
К=2; x1=-П/6+П•2/2=-П/6+П=5П/6
K=3;x2=-П/6+П•3/2=-П/6+3П/2=-П/6+9П/6=8П/6=4П/3
BC
sin A= -----
AB
BC=AB*sinA
BC=10*0,9=9
6х-12х-4х+8=0
-10х=-8
х=0,8