Fold a shape and both halves match — that's line symmetry. Spin a shape and it looks the same partway through a turn — that's rotational symmetry. Some shapes have both.
A shape has a line of symmetry if folding along that line makes both halves match exactly.
| Shape | Lines of symmetry |
|---|---|
| Equilateral triangle | 3 |
| Square | 4 |
| Rectangle | 2 |
| Regular pentagon | 5 |
| Regular hexagon | 6 |
| Circle | infinite |
Spin a shape around its centre. If it looks EXACTLY the same before completing a full turn, it has rotational symmetry. The order is how many times it matches in one full turn.
| Shape | Order of rotational symmetry |
|---|---|
| Equilateral triangle | 3 |
| Square | 4 |
| Rectangle | 2 |
| Regular pentagon | 5 |
Rule: a REGULAR polygon's order of rotational symmetry always equals its number of sides.
A regular polygon always has BOTH kinds of symmetry — and for regular shapes, the two counts always match.
12 IMO-style questions on line and rotational symmetry. 🍀