trigonometry - Is $\sin^3 x=\frac{3}{4}\sin x - \frac{1}{4}\sin 3x$? - Mathemati
$$\sin^3 x=\frac{3}{4}\sin x - \frac{1}{4}\sin 3x$$ Is there any formula that tells this or why is it like that? ... de Moivre's formula says $$ \begin{align} \cos(3x)+i\sin(3x) &=(\cos(x)+i\sin(x))^3\\ &=...