Shapes with one or more lines of Symmetry

Taj Mahal is a remarkable example of symmetry.

A line drawn as shown divides it into two halves that exactly match each other.

Such structures are said to be symmetric. And the line is called Line of symmetry.

One more example of symmetry.

When the picture is folded in half, the right and left halves match.

Also one half fits exactly over the other.

The line representing the fold is called a line of symmetry for the picture.

Observe that when a mirror is placed along the line of symmetry.

The mirror image represents the right half.

So this line of symmetry is also called as mirror line.

Similarly in geometry, various basic shapes have symmetry.

Let us look at a few geometric shapes that have symmetry.

For a rectangle, one half exactly fits the other when folded length wise.

Also, one half exactly fits the other when folded breadth wise.

These two folds are nothing but the lines of symmetry of the rectangle.

So a rectangle has two lines of symmetry.

Similarly a square when folded along the sides has symmetry.

A square also has lines of symmetry along the diagonals

So a square has 4 lines of symmetry.

An equilateral triangle, when folded along the lines shown will have symmetry.

So an equilateral triangle has three lines of symmetry.

An isosceles triangle has only one line of symmetry along a line between equations sides.

A regular pentagon has line of symmetry through the mid point of each of its sides.

So a regular pentagon has lines of symmetry.

Revision

A line that divides a given shape into identical halves is called the line of symmetry

Line of symmetry is also called a mirror line.

A rectangle has 2 lines of symmetry.

A square has 4 lines of symmetry.

An equilateral triangle has 3 lines of symmetry

An isosceles triangle has one line of symmetry

A regular pentagon has five lines of symmetry.

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