$\tan(\alpha)=\alpha$ has not complex roots?

93 Views Asked by At

By the Strum theory it is easy to see that the equation $\tan(\alpha)=\alpha$ has not complex roots and it's real roots occur at zero and near $(2n+1)\pi/2,\ n\in Z^{+}$. I am interesting to know that is there any other way to see that the above equation has not complex roots?