Polygon - GCSE Maths Definition

Polygon is the general name for any two-dimensional shape that has straight sides (edges). The number of angles a polygon has will be equal to its number of sides. (Adjacent) sides of a polygon meet at a vertex. The number of vertices a polygon has will also be equal to its number of sides. In diagrams, vertices are usually referred to using capital letters (A, B, C, ..) and if drawn on coordinate axes, each vertex can be referenced by coordinates (e.g. (-2, 3)). A regular polygon will have all its sides of equal length, and all of its angles of equal size.

Specific polygons are named by their number of sides/angles. We start with a triangle with 3 sides and angles (note it is impossible to have a polygon with less than 3 sides); a quadrilateral has 4 sides and angles; 5 of each for a pentagon; 6 for a hexagon, 7 for a heptagon (also called a septagon); 8 for an octagon; 9 for a nonagon, 10 for a decagon.

In GCSE Mathematics, you may be required to solve problems involving the properties of common polygons, which may or may not be regular. Questions could include finding unknown side lengths, unknown angles, perimeters and areas.