2(1-sin^2x)+5sinx-4=0
2-2sin^2x+5sinx-4=0
2sin^2x-5sinx+2=0
(5+-sqrt(25-16))/4
(5+-3)/4
-1<=sinx<=1
sinx=1/2
x1=П/6+2Пk
x2=5/6П+2Пk
2(1-sin^2x)+5sinx-4=0
2-2sin^2x+5sinx-4=0
2sin^2x-5sinx+2=0
(5+-sqrt(25-16))/4
(5+-3)/4
-1<=sinx<=1
sinx=1/2
x1=П/6+2Пk
x2=5/6П+2Пk