Triangles, quadrilaterals and other polygons

A polygon is simply a closed shape made up of straight lines. Regular polygons have all sides equal and all angles equal, like a square or equilateral triangle. Irregular polygons have sides and angles of different lengths and sizes, like a rectangle or the shape of Nigeria's map itself.

When you're constructing regular polygons in technical drawing, you'll use compass and ruler to ensure perfect measurements. For irregular polygons, you follow given dimensions without worrying about making everything match. Think of constructing a regular hexagon for a honeycomb design versus drawing an irregular plot of land—one follows strict rules, the other doesn't.

Understanding properties like the sum of interior angles helps you verify your constructions. For a polygon with n sides, interior angles sum to (n-2) × 180°.