The dotted line which is the half part of each shape to one side of a dotted line is the mirror image of the other parts is called the line of symmetry . In another word, it is also called the axis of symmetry , so the figure is said to have bilateral symmetry or to be symmetrical by reflection in the dotted line and a line of symmetry shape can be turned so as it exactly into its outline.
Rotational symmetry
When a shape can be mapped onto itself by a rotation of less than a complete turn (360^{o}) about a point the shape is said to have a rotational symmetry .
Order of rotational symmetry
When the shape is rotated through a half -turn it can be fitted to the original shape . It means , when it is rotated through 2 times half-turns , it reaches its original position .
\(\therefore\) It has rotational symmetry of order 2.
When the equilateral triangle is rotated through a \(\frac{1}{3}\) of turn 120^{o}, it can fit over the original shape. When it is rotated through3 times \(\frac{1}{3}\) and then it will reach its original place.
\(\therefore\) It has rotational symmetry of order 3.
When the square is rotated through quarter-turn \(\frac{1}{4}\)of the turn 90^{o}. Which can be fitted over the original shape . It means when it is rotated through 4time \(\frac{1}{4}\)of turn , it reaches its original position .
\(\therefore\) It has rotational symmetry of order 4.
Tessellation
A tessellation is known as tiling . It is covering of the plane with congruent geometrical shape un which a repeating pattern without leaving any gaps and without overlapping each other.The shape is polygons in it . It may be an equilateral triangle , regular hexagon or square . To make a tessellation :
Types of tessellation
The process of covering of the plane with congruent geometrical shapes in a repeating pattern without leaving any gaps and without overlapping each other is known as ______.
Tessellation is also known as ______ .
When a shape can be mapped into itself by a rotation of less than a complete turn around a point, the shape is said to be ______ .
Tessellation should not have any gaps and ______ .
Tessellation is done on the surface of floor and ______ .
ASK ANY QUESTION ON Symmetry, Design and Tessellations
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