This Problem Was Made In 2016

Geometry Level 5

$\begin{cases} x^3+3x^2+2019x+2017=\sin^2\theta - \frac{1}{2} \\ y^3+3y^2+2019y+2017=\cos^2\theta - \frac{1}{2} \end{cases}$

Given that $x$ , $y$ and $\theta$ (measured in radians) are real numbers satisfying the system of equations above, find the value of $x+y$ .