2 3 3*cos (x)*sin(x) - sin (x) <= 1/2
-sin(x)^3 + sin(x)*(3*cos(x)^2) <= 1/2
pi 5*pi 2*pi [0, --] U [----, ----] 18 18 3
x in Union(Interval(0, pi/18), Interval(5*pi/18, 2*pi/3))
/ / pi\ /5*pi 2*pi\\ Or|And|0 <= x, x <= --|, And|---- <= x, x <= ----|| \ \ 18/ \ 18 3 //
((0 <= x)∧(x <= pi/18))∨((5*pi/18 <= x)∧(x <= 2*pi/3))