Symmetry in Real Life
If an object has symmetry or is symmetrical it has a balanced look. There is line symmetry which is similar to an object being seen in a mirror and rotational or turning symmetry which is about rotating objects around thier centre point.
There are two types of symmetry: line symmetry, which involves reflection , and rotational symmetry, which involves rotation .
A figure has a line of symmetry if it maps or folds onto itself under reflection in the line. The figure is divided by the line into two parts which are identical.
Line m is called the mirror line or axis of symmetry.
Different shapes can have various numbers of axes of symmetry. e.g.
A figure has rotational symmetry if it can be rotated around a point, called the centre of rotation so that if fits exactly onto itself.
All figures have an order of rotational symmetry of at least 1.
The order of rotational symmetry is the number of times the shape fits onto itself during a rotation of 360°
Total Order of Symmetry
The table shows the symmetry properties of some common shapes.
A figure has point symmetry if it maps onto itself under a rotation of 180° (a half turn). e.g. A parallelogram.