If $\alpha_1, \alpha_2, \alpha_3 \ldots, \alpha_n$ are real numbers, $\alpha_1 \neq 0$ and $z=\cos \theta+i…
If $\alpha_1, \alpha_2, \alpha_3 \ldots, \alpha_n$ are real numbers, $\alpha_1 \neq 0$ and $z=\cos \theta+i \sin \theta$ is a root of the equation $\alpha_1+\alpha_2 z+\alpha_3 z^2+\ldots+\alpha_n z^{n-1}+z^n=0$, then $\alpha_1 \cos n \theta+\alpha_2 \cos (n-1) \theta+\ldots+\alpha_n \cos \theta=$