Mathematics for IGCSE & O level - Symmetry (Section 1 - No. 32)
How is line symmetry defined?
The number of times a shape looks the same in a full turn.
When a shape can be folded in half and the two halves match exactly.
The degrees of rotation.
When the shape has no symmetry
Explication
Line symmetry is defined as a shape that can be folded and the two halves match.