Symmetry

In geometry, symmetry describes the balance a figure has. Both plane and space figures may have symmetry.


line symmetry


A plane figure has line symmetry if it can be divided into two congruent parts that are mirror images. Notice that each line of symmetry creates a mirror image, or reflection:

Line symmetry is also referred to as reflectional symmetry.


plane symmetry


A space figure has plane symmetry if it can be divided into two halves that are reflections of each other.


rotational symmetry


A plane figure, such as a snowflake, has rotational symmetry if, when rotated less than a full turn around a fixed point, the shape of the figure moves onto itself.

A space figure, such as a top, has rotational symmetry if the shape of the figure moves onto itself when rotated less than a full turn around a fixed point.


Related word asymmetrical, symmetrical.

See also line symmetry, rotational symmetry, symmetric property of equality.