6-6sin²x+5sinx-2=0
sinx=a
6a²-5a-4=0
D=25+96=121
a1=(5-11)/12=-1/2
sinx=-1/2
1)x=-π/6+2πn,n∈z
-5π/2≤-π/6+2πn≤-π
-15≤-1+12n≤-6
-14≤12n≤-5
-7/6≤n≤-5/12
n=-1⇒x=-π/6-2π=-13π/6
2)sinx=7π/6+2πk,k∈z
-5π/2≤7π/6+2πk≤-π
-15≤7+12k≤-6
-22≤12k≤-13
-11/6≤k≤-13/12
нет решения
a2=(5+11)/12=4/3
sinx=1 1/3>1
нет решения