Lesson 60: Polygons

New Concept

Polygons are closed, flat shapes with straight sides.

What’s next

Next, we'll practice identifying, naming, and describing different types of polygons. You will also see worked examples using their properties.

Property

Polygons are closed, flat shapes with straight sides.

Examples

• A stop sign is a polygon because it is a closed, flat shape with 8 straight sides.
• A perfect circle is not a polygon because its entire edge is one continuous curve.
• The letter 'S' is not a polygon because it is an open shape and has curves.

Explanation

Think of a polygon as a perfectly secure fence! For a shape to count, it must be completely closed with no escape gaps, it must be flat on the ground (2D), and it must be built with straight sections, not curvy ones. Any shape that breaks these rules is an imposter!

Property

Polygons are named by the number of sides they have. The prefix of a polygon's name tells how many angles and sides the polygon has: tri- means 3, quad- means 4, and penta- means 5.

Examples

• A shape with six sides is called a hexagon, because the prefix hexa- means six.
• A polygon with four sides is called a quadrilateral, which is the general name for all four-sided shapes.
• Since penta- means five, a pentagon is a polygon that always has exactly 5 sides.

Explanation

Naming polygons is like learning a secret code where the first part of the word reveals its identity! The prefix, like 'octo-' or 'hexa-', tells you exactly how many sides and corners the shape has. Master the prefixes, and you'll be a polygon-naming ninja in no time!