Identify polygons

A polygon is a closed, two-dimensional shape formed entirely by straight line segments, with each segment meeting another at a vertex; its identity depends on this structure, not its size, orientation, or appearance. Shapes are identified and named by the number of sides and vertices—such as triangles, quadrilaterals, pentagons, and hexagons—and distinguished from open figures, curved shapes, and three-dimensional solids, without formal analysis of complex or self-intersecting figures.

Detailed Explanation: Identify polygons

A polygon is a flat, closed shape made only of straight line segments.

To identify a polygon:

Check that the shape is closed.
Check that all its sides are straight.
Count the sides, which is also the number of vertices (corners).
Use the number of sides to name the shape.

Example

A shape has 5 straight sides. Each side meets the next side, and the shape is closed.

It is closed.
All of its sides are straight.
It has 5 sides and 5 vertices.
A polygon with 5 sides is called a pentagon.

So, the shape is a pentagon.

The shape’s size or how it is turned does not change its name. A pentagon can be small, large, tilted, or upside down and still be a pentagon.

Learn by doing: Identify polygons

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Classifying Polygons by Sides (Real World)

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