Two halves which match perfectly

Mirror Play Well before children begin any formal study of symmetry, playing with mirrors — perhaps on Pattern Block designs that they build — develops experience and intuition that can serve both their geometric thinking and their artistic ideas. The same is true of the letter M. Letters like B and D have a horizontal line of symmetry: their top and bottom parts match. Some letters, for example, X, H, and O, have both vertical and horizontal lines of symmetry. And some, like P, R, and N, have no lines of symmetry.

The letters, N, Z, and S also share that property. The most symmetric shape A circle has infinitely many lines of symmetry: any diameter lies on a line of symmetry through the center of the circle.

Related posts. Shape: Equiangular Read more. Language and Mathematics Read more. List of Topics. What are symmetrical shapes? What are lines of symmetry? How to draw symmetric figures and patterns? If a figure can be folded or divided into half so that the two halves match exactly then such a figure is called a symmetric figure.

The figures below are symmetric. The dotted line in each of the symmetric figures above that divides the figure into two equal halves is called the line of symmetry.

In the figures above, there are no lines of symmetry that divide each of the figures into two equal halves.

Therefore, these figures are not symmetric. The heart cannot be further folded to get the equal halves. Hence, the heart has only one line of reflection symmetry. As shown above, the rectangle can be divided into two equal halves either along the vertical line or along the horizontal line. Hence, a rectangle is said to have two axis of reflection symmetry. One must note that not all shapes or figures have reflection symmetry. There are numerous shapes that cannot be divided into two congruent halves.

Such shapes are called asymmetrical. This triangle cannot be divided into equal halves and hence does not have reflection symmetry. Reflection symmetry can also be illustrated by everyday objects like given below: Explain how many lines of reflection symmetry do circle, square and an equilateral triangle have? Since a circle can be divided into equal halves along its diameter and the fact that infinite diameters can be drawn for a circle, a circle is said to have infinite lines of symmetry.

A square can be divided into equal halves by dividing horizontally, vertically or diagonally. Hence, a square is said to have 4 lines of symmetry. Since the sides of an equilateral triangle are equal, it can be divided into equal halves by lines drawn from midpoint of a side joining the opposite vertex.

So, an equilateral triangle has 3 lines of symmetry. The isosceles triangle has two equal sides and therefore the line of symmetry or the reflection symmetry is two. In all the above examples, there was only one line dividing the figure into two halves.

There are many 3D objects where planes and not lines divide an object into two equal and congruent halves. Such planes are called planes of symmetry or planes of reflection.