Measure of an exterior angle of a 12-gon?

To find an exterior angle of a regular 12-gon, use the formula to find the total sum of all the angles first: total sum of all angles = (n-2)*180
where 'n' is the number of sides, or 12.

By solving, you will find that the total sum of all angles is 1800 degrees, so since it is a regular polygon, you can divide by 12 to find the measure of each interior angle, which is 150 degrees.


Once you know the measure of the interior angles, since an exterior angle is the supplement of an interior angle, subtract 150 degrees from 180 degrees (the measure of a straight line) to find the exterior angles, which will be 30 degrees.