Two-Dimensional Figures
Definition of a polygon: a geometric figure that is made up of 3 or more line segments that intersect only at their endpoints. The number of sides determines the name of the polygon.
Definition of a regular polygon: a polygon with all sides equal in length and all angles equal in measure. Matching angle marks indicate that the angles are congruent. The figures below are examples of regular polygons. You can draw diagonals to divide the polygon into triangles to find the sum of the measures of their angles.