Answer: The required degree of rotation of the given polygon is 18°.
Step-by-step explanation: We are given to find the degree of rotation of a regular 20-sided polygon.
We know that
if a regular polygon has n number of sides, then its degree of rotation is given by

For the given polygon, we have
n = 20.
Therefore, the degree of rotation of the given polygon is

Thus, the required degree of rotation of the given polygon is 18°.