Number of sides in polygons

Key Notes:

🔷 What is a Polygon?

  • A polygon is a closed figure made of straight lines.
  • It has no curves and no open sides.

🔷 Types of Polygons Based on Number of Sides

Polygon NameNumber of Sides
Triangle3 sides
Quadrilateral4 sides
Pentagon5 sides
Hexagon6 sides
Heptagon7 sides
Octagon8 sides
Nonagon9 sides
Decagon10 sides

🔷 More Important Points

  • All polygons must have at least 3 sides.
  • The name of the polygon usually tells how many sides it has.
  • Regular polygons have equal sides and equal angles.
  • Irregular polygons have different side lengths or angles.

🔷 Examples in Real Life:

  • Triangle – road signs.
  • Quadrilateral – TV screen.
  • Hexagon – honeycomb.
  • Octagon – stop sign.

🔷 Fun Tip:

The word “gon” means “angle” in Greek, so polygon names often end in -gon!

Learn with an example

🎯 How many sides does a pentagon have?

  • 5
  • 8
  • 9
  • 10

This is a pentagon:

A pentagon has five sides.

🎯 How many sides does a nonagon have?

  • 6
  • 5
  • 9
  • 8

This is a nonagon:

A nonagon has nine sides.

🎯 How many sides does a triangle have?

  • 6
  • 4
  • 9
  • 3

This is a triangle:

A triangle has three sides.

let’s practice!