1. According to the plot, this happens twice for some
between 135° and 180°, and for some
between 270° and 315°.
We could try finding them exactly, but we would end up having to solve a 4th degree polynomial equation that doesn't factorize nicely...
2. Rewrite the inequality as
The curve
lies above
when
, where
is the first solution mentioned in (1) between 135° and 180°, approximately
.
3. Rewriting
we see from the plot that this is true for
between 45° and 90°, and again between 225° and 270°.