What Have We Discussed?
A figure has line symmetry, if there is a line about which the figure may be folded so that the two parts of the figure will
Regular polygons have equal sides and equal angles. They have multiple (i.e., more than one) lines of
Each regular polygon has as many lines of symmetry as it has sides.
| Regular Polygon | Regular hexagon | Regular pentagon | Square | Equilatera triangle |
|---|---|---|---|---|
| Number of lines of symmetry | 6 | 5 | 4 | 3 |
Mirror reflection leads to symmetry, under which the left-right orientation have to be taken care of.
Rotation turns an object about a fixed point. This fixed point is the centre of rotation. The angle by which the object rotates is the angle of rotation. A half-turn means rotation by
If, after a rotation, an object looks exactly the same, we say that it has a
In a complete turn (of 360°), the number of times an object looks exactly the same is called the
The order of symmetry of a square, for example, is 4 while, for an equilateral triangle, it is
Some shapes have only one line of symmetry, like the letter E; some have only rotational symmetry, like the letter S; and some have both symmetries like the letter H. The study of symmetry is important because of its frequent use in day-to-day life and more because of the beautiful designs it can provide us.