What is the size of an exterior angle of a regular polygon with 12 sides?

To find the size of an exterior angle of a regular polygon with 12 sides, follow these steps:

1. Understand the formula for the exterior angle of a regular polygon: The formula for the exterior angle of a regular polygon is given by: $\text{Exterior Angle} = \frac{360^\circ}{n}$ where $n$ is the number of sides of the polygon.

2. Substitute the number of sides into the formula: For a polygon with 12 sides, $n = 12$.

3. Calculate the exterior angle: $\text{Exterior Angle} = \frac{360^\circ}{12}$

4. Perform the division: $\text{Exterior Angle} = 30^\circ$

Therefore, the size of an exterior angle of a regular polygon with 12 sides is $30^\circ$.