What is an axis of symmetry?
An axis of symmetry is a straight line that splits a shape into two halves that match exactly. If you fold the shape along that line, one half lands right on top of the other. It is also called a line of symmetry.
Counting the lines
Some shapes have more than one axis of symmetry:
- A square has 4 lines of symmetry.
- A rectangle has 2.
- A circle has very many (a line through the centre in any direction).
- A letter like A has 1 (a vertical line down the middle).
Worked example
Does the letter H have an axis of symmetry? Fold it top to bottom — the halves match. Fold it left to right — the halves match too. So the letter H has 2 axes of symmetry.
Remember
- Fold test: if both halves match, that fold line is an axis of symmetry.
- A shape can have 0, 1, or many axes of symmetry.