The sum of the interior angles is: All the interior angles in a regular polygon are equal. The formula for calculating the size of an interior angle is: \(\text{interior angle of a polygon} ...

so the formula is more useful here. (53 – 2) × 180 = 51 × 180 = 9180. The interior angles of a 53-sided polygon sum to 9180°. A regular polygon is a polygon with all sides and angles equal.