Problem:Find all solutions of $\displaystyle z^{3} = -8$.

I can do the entire problem except for one part. After putting it into the correct form,

$\displaystyle |z|^{3}(cos3\theta+isin3\theta)$,

I do not know how to find the values of $\displaystyle cos3\theta$ or $\displaystyle sin3\theta$. I know that $\displaystyle |z|^3$ is 8, but I can't figure out the values of cos and sin.

Any help is appreciated.