Draw a figure using only straight line pieces, without taking the pencil off the paper, until you return to the beginning without crossing the path. You drew a polygon!

What is a polygon

DefiniçãoPolygon

A polygon is a flat closed figure, formed only by pieces of straight lines (the sides) that do not intersect. The points where two sides meet are the vertices.

The circle is not a polygon: its contour is curved. An open figure is also not a polygon.

Choose the number of sides and drag the yellow balls. What happens when two sides cross?

The names of the polygons

Every polygon has the same number of sides and vertices. The name tells how many there are:

Sides Name Remember
3 triangle “tri” = three, as in tricycle
4 quadrilateral “quadri” = four
5 Pentagon the Pentagon building in the United States
6 hexagon honeycomb
8 octagon the STOP sign

Quadrilaterals: the family of four sides

Among the quadrilaterals, some have special names: the square, the rectangle, the rhombus (like the yellow warning sign), the parallelogram and the trapezoid. You will study them with Calm down in Elementary II.

Check the answer

Triangle: 12 ÷ 3 = 4 sticks on the side. Square: 12 ÷ 4 = 3 sticks. Hexagon: 12 ÷ 6 = 2 sticks.

True or false?

  1. A pentagon has 5 sides and 5 vertices.
  2. The circle is a polygon.
  3. The square is a quadrilateral.
  4. A figure with intersecting sides, like an hourglass, is a simple polygon.