Definition:Root of Unity/Complex/First

Definition
Let $n \in \Z_{>0}$ be a (strictly) positive integer.

In Complex Roots of Unity in Exponential Form it is shown that the complex $n$th roots of unity are the elements of the set:
 * $U_n = \left\{{e^{2 i k \pi / n}: k \in \N_n}\right\}$

The root $e^{2 i \pi / n}$ is known as the first $n$th root of unity.