If n is a positive integer, the complex number has exactly n distinct n th roots.

The roots are , where

The complex number is 5i.

 Compare the complex number with a + ib.

a = 0 and b = 5.

a = 0  so, the angle is :

The trigonometric form of 5i is .

The square roots of are :

, here n = 2 and k = 0 and 1

If k = 0, the root

If k = 1, the root

The square roots of the complex number are .