What is a symmetry?

A shape has line symmetry (or reflective symmetry) when you can draw a line through it so that one side is an exact mirror image of the other. That line is called the line of symmetry. A shape can have no lines of symmetry, one, or many.

Examples

• A square has 4 lines of symmetry.
• A butterfly is symmetrical down the middle.
• The letter A has 1 line of symmetry; S has none.

Quick facts

• A circle has infinitely many lines of symmetry.
• If you fold a shape along its line of symmetry, the two halves match exactly.