In mathematics we are often interested in categorising things, which we do by looking for common properties.

There are many ways to classify shapes. We can classify them based on:

• Number of sides;
• Number of vertices;
• Size of angles;
• Lines of symmetry.

What different shapes do you know based on the number of sides they have?

Thinking about only 3-sided shapes, how many different special 3-sided shapes do you know the names of? What are the properties of these shapes?

Thinking about only 4-sided shapes, how many different special 4-sided shapes do you know the names of? What are the properties of these shapes?

Exercise

Let’s try the short exercise of the first three questions on exercise 3J on page 54 (make sure to write the full sentence if a missing word is required):

The answers are below: