A shape is said to have Line Symmetry (often called Reflection Symmetry or Mirror Symmetry) when it can folded in half so that both halves match. If a mirror is placed along the line of the fold (called the 'line of symmetry' or 'mirror line') then the shape will look the same as without the mirror.
If a shape can be divided into identical mirror images by a line of symmetry it is said to be symmetrical. Lines of symmetry can be any direction and shapes can have more than one .
Examples of lines of symmetry.
Two lines of symmetry
Four lines of symmetry
No lines of symmetry
One line of symmetry
Three lines of symmetry
Six lines of symmetry
With a circle, any line that goes through the centre is a line of symmetry!
Therefore this shape has an infinite number of lines of symmetry.
Practice working with Symmetry with these worksheets from Primary Resources