General Certificate of Secondary Education (GCSE) Maths Practice Exam 2026 - Free Maths Practice Questions and Study Guide

To calculate the individual interior angles of a regular polygon, the formula used is (n-2) x 180/n, where n represents the number of sides in the polygon.

This formula derives from the fact that the sum of the interior angles of any polygon can be determined by the equation (n-2) x 180. This accounts for the fact that a polygon can be divided into (n-2) triangles, as each triangle contributes 180 degrees to the total sum of angles.

Once the total interior angle sum is calculated, dividing that sum by the number of sides (or angles) n gives the measure of each individual interior angle, which is why we have the formula rearranged to (n-2) x 180/n.

This approach allows for easy calculation of angles in regular polygons where all angles are equal, making option B the correct choice for determining individual interior angles.