Good afternoon. I want some help in this exercise:

Solve in R the equation $\displaystyle 4x\sin(\omega x) - x^2 - 4 = 0$

I have tried to convert it in a perfect square form but i came out with this $\displaystyle (x - 2 \sin(\omega x))^2 + 4 (\cos(\omega x))^2 = 0$ and i can't solve this. Can anyone help, please?