What Is a Line of Symmetry? Definition, Types, Shapes, Examples (2024)

What is a Line of Symmetry?

In mathematics, an object is said to have symmetry if it can be divided into two identical halves. The line that divides the object into its identical halves is called the line of symmetry. For example, in the given image, the line passing through the middle of the flower is its line of symmetry.

Definition of Line of Symmetry

A line of symmetry is the line that divides a shape or an object into two equal and symmetrical parts. We also call this line the axis of symmetry or mirror line because it divides the figure symmetrically, and the divided parts look like mirror reflections of each other. More line of symmetry examples are shown in the figure below.

Symmetric and Asymmetric Figures

A figure or shape that can be divided into two equal parts by a line is called symmetric figures. The shapes and objects that are irregular and do not resemble each other when divided into two parts are called asymmetric figures.

Types of Lines of Symmetry

The line of symmetry can be categorized based on the basis of its orientation.

Horizontal Line of Symmetry: If a horizontal line divides an object into two identical halves, it is called a horizontal line of symmetry. That means the horizontal line of symmetry goes from left to right (or vice versa) in an object.

Vertical Line of Symmetry: If a vertical line divides an object into two identical halves, it is called a vertical line of symmetry. That means that the vertical line goes from top to bottom (or vice versa) in an object and divides it into its mirror halves.

Diagonal Line of Symmetry: If a diagonal line divides an object into two identical halves, it is called a diagonal line of symmetry. That means the diagonal line of symmetry goes sideways or slanting in an object.

Number of Lines of Symmetry in a Shape

The line of symmetry produces reflections that coincide. A shape or an object can have multiple lines of symmetry as per its structure. Shapes with one line of symmetry have only one line that divides them into identical parts. Shapes with multiple lines of symmetry have more than one line that divides them equally. The axis of symmetry can be horizontal, vertical or diagonal. For example,

Line of Symmetry in Geometry

Axis of symmetry in common two-dimensional geometrical shapes are given below:

Geometric shapes can have more than one line of symmetry. Let us study some geometric shapes with one and multiple axes of symmetry.

Solved Examples on Line of Symmetry

Example 1: How many lines of symmetry do the given figure have?

Solution: The given figure only has one line of symmetry.

Example 2: Identify whether the given line of symmetry is a vertical, horizontal, or diagonal line of symmetry.

Solution: The given line is a vertical line of symmetry.

Example 3: Write three capital letters in the English alphabet have no lines of symmetry?

Solution: The three letters in the English alphabet that have no lines of symmetry are P, G, and J.

Example 4: Write three capital letters in the English alphabet with horizontal and vertical lines of symmetry.

Solution:The English alphabets with horizontal and vertical lines of symmetry are H, I and O.

Practice Problems on Line of Symmetry

Conclusion

Lines of symmetry can help children understand and create patterns. It teaches a sense of balance and order and opens them up to the natural world where symmetry abounds—insects, seashells, and leaves, to name a few.
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Frequently Asked Questions on Line of Symmetry