book

Year 5 Maths

maths owl

Polygons

triangle

When sides join up to make a closed flat figure around a space, you have a polygon. Can you draw a closed figure with just one straight side? How about two? Even if you return to your starting point, all you have is a straight line segment. For a polygon, you need at least three. The name comes from a Greek word for ‘many angles’.

Polygons have the same number of sides, vertices and angles. Every side makes an angle with the next side around. Every angle is positioned at a vertex.

A triangle has three angles. How many sides?

A quadrilateral has four sides. How many angles?

quadrilateral

A pentagon has five angles. How many vertices? How many sides?

pentagons

We say that a polygon is regular when all of its angles are equal and all of its sides are the same length. An irregular polygon has some angles that are different or some sides that are different lengths.

triangle

To give polygons names, we put letters at the vertices. Look at triangle FGH and hexagon LMNOPQ. Can you work out what a hexagon is? It is a polygon with six sides, six vertices and six angles.




This activity is adapted from pages 269-270 of What Your Year 5 Child Needs to Know, which can be purchased here.