-4sin^(2)x<-1
sin^(2)x>1/4
(1-cos2x)/2>1/4
1-cos2x>1/2
cos2x<1/2
2x<+(-)arccos1/2+2πn
2x<+(-)π/3+2πn
x<+(-)π/6+πn
-4sin^(2)x<-1
sin^(2)x>1/4
(1-cos2x)/2>1/4
1-cos2x>1/2
cos2x<1/2
2x<+(-)arccos1/2+2πn
2x<+(-)π/3+2πn
x<+(-)π/6+πn