1 + 2*sin(x) > cos(x)
2*sin(x) + 1 > cos(x)
And(0 < x, x < pi + atan(4/3))
(0 < x)∧(x < pi + atan(4/3))
(0, pi + atan(4/3))
x in Interval.open(0, atan(4/3) + pi)