Definition
Line of symmetry
A line of symmetry divides a figure into mirror-image halves that match exactly.
Continue from this idea into connected AXIO math.
What it means
Imagine folding the figure along the line. If every part lands exactly on a matching part, the fold line is a line of symmetry. The two sides face opposite ways, but their shapes and distances from the line must match.
Remember it
Fold on the line; matching halves land together.
Example
A non-square rectangle has two lines of symmetry: one vertical and one horizontal through its centre. A diagonal is not a line of symmetry because the long and short sides do not land on matching sides.
Watch for
A line that merely splits a figure into two equal areas is not necessarily a line of symmetry; reflection must make the complete figure match.
Common mix-up
A diagonal can be a line of symmetry for a square, but not for every rectangle.
Exact meaning
A line of symmetry is a line such that reflecting a figure across it maps the figure exactly onto itself. Corresponding points lie the same perpendicular distance from the line on opposite sides.