Modulus of Complex Root of Unity equals 1

Theorem
Let $n \in \Z_{>0}$ be a (strictly) positive integer such that $n$ is even.

Let $U_n = \set {z \in \C: z^n = 1}$ be the set of complex $n$th roots of unity.

Let $z \in U_n$.

Then:
 * $\cmod z = 1$

where $\cmod z$ denotes the modulus of $z$.