Polygons

📖 In short

A polygon is a flat, closed shape whose sides are straight lines. A triangle is a polygon, and so are a square and a rectangle. But a circle isn't a polygon, because its edge is curved. A polygon is named after how many sides it has.

🤩 Did you know?

A polygon's perimeter is the sum of the lengths of its sides.
A triangle's angles add up to 180 degrees, and a quadrilateral's to 360 degrees.
The exterior angles of any polygon add up to 360 degrees.
Many Islamic decorations are built from polygons and stars.

🔎 Find out more

🌟 Names of polygons

A polygon with three sides is a triangle, with four a quadrilateral, with five a pentagon, with six a hexagon, and with eight an octagon, like the shape of a “Stop” sign on the road.

🔍 Sides and corners

The point where two sides meet is called a vertex. Every polygon has as many vertices as sides: a triangle has three sides and three vertices.

💡 Regular polygons

If all the sides of a polygon are equal and all its angles are equal, it's called a regular polygon, like a square or a regular hexagon.

🎯 Polygons in nature

Bees build their wax cells as regular hexagons, because this shape fills space with no gaps and needs the least wax. How clever bees are!

🧩 Test yourself

1 How many sides does a hexagon have?

2 Why isn't a circle a polygon?

3 The exterior angles of any polygon add up to ?? degrees.

4 Which picture shows “Polygons”?