What is Symmetry?
Have you ever noticed how a butterfly's wings look the same on both sides? Or how your face looks roughly the same on the left and right? That's symmetry in action — and it's everywhere in nature, art, and design.
In mathematics, symmetry is about balance and identical patterns. When we study line symmetry, we're looking at whether a shape can be folded along a line so that both halves match up perfectly.
A shape has symmetry when one part of it is a mirror image of another part.
Think of folding a piece of paper in half. If you cut out a shape while the paper is folded and then unfold it, both sides will be identical. That fold line is a line of symmetry.
Lines of Symmetry
A line of symmetry (also called a mirror line or axis of symmetry) is an imaginary line that divides a 2D shape into two halves that are exact mirror images of each other.
A line that divides a shape into two identical halves, where one half is the mirror image of the other. If you fold the shape along this line, both halves overlap perfectly.
Key things to remember:
- The two halves must be exactly the same shape and size
- If you place a mirror along the line of symmetry, the reflection would complete the shape perfectly
- Lines of symmetry can be vertical, horizontal, or diagonal
To test if a line is truly a line of symmetry, imagine folding the shape along that line. If every point on one side lands exactly on a matching point on the other side, it's a genuine line of symmetry.
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