Polygons are closed, flat shapes made of straight lines. Each line segment meets exactly two others to form corners, called vertices.
A circle is not a polygon because its sides are curved, not straight.
Each polygon has sides, vertices (corners), and angles. The number of sides a polygon has also tells you its name.
Every vertex of a polygon connects two sides. The sum of all sides forms the perimeter.
Polygons can be classified by the number of sides or by whether they are regular or irregular.
Remember: the shape’s name comes from how many sides it has, not whether it is regular or irregular.
A convex polygon has all angles pointing outward. A concave polygon has at least one angle that points inward, or one diagonal that lies outside the shape.
In a convex polygon, all interior angles are less than 180°. In a concave polygon, at least one interior angle is greater than 180°.
To identify a polygon, count its sides, check that all sides are straight, and make sure it is a closed shape.
Polygons are named by combining Greek or Latin prefixes with “-gon.” For example, “penta” means five, so a polygon with five sides is a pentagon.
Polygons appear in many places around us, such as buildings, road signs, tiles, and artwork. Recognizing them helps us understand shapes and design in everyday life.
When you notice shapes in your surroundings, you strengthen your geometry skills and learn how math connects to the real world.