WBBSE Notes For Class 6 Maths Geometry Chapter 6 Symmetry

Geometry Chapter 6 Symmetry

Geometry Chapter 6 What is meant by symmetrical body

1. We are always facing some bodies or some figures of bodies that have some similarities.
2. Again times, we observe that there exist similarities between two halves of the same body or the figure of the same body.
3. For example, our left and right hands there exist some similarities of these two hands.
4. Again if we draw a straight line along the middle of the figure of the butterfly and after folding two halves of the butterfly along this line, we see that these two halves will coincide completely.
5. So if we find replaceable similarities (i.e., one body is completely identical with the other body) of two or more bodies, then these bodies are called Similar to each other.

 

 

 

 

WBBSE Class 6 Symmetry Notes

Definition:

If there exists a replaceable similarity (one part is completely identical to the other part) of two halves of a body or the figure of that body, then this body or the figure of that body is called a symmetrical body or the figure of a symmetrical body.

Classification of Symmetry :

Symmetry is generally classified into two types.

1. Linear Symmetry

2. Rotational Symmetry

Linear Symmetry:

1. When a body or a figure of the body is such that with respect to a straight line the body or its figure can be divided into two exactly equal parts i.e. if a body or its picture is folded along a straight line, one part will coincide with the other part, then the body or its picture is called a Linear Symmetrical body.

For example, any equilateral triangle is symmetrical with respect to its media.

1. Line of Symmetry:

1. The straight line about which the two parts of the body or its picture are equal or identical completely is called the line of Symmetry.
2. A body or its picture can be symmetrical with respect to more than one straight line.
3. So a body or its picture may have more than one line of symmetry.

Important Definitions Related to Symmetry

2. Rotational Symmetry :

1. If a body or a figure is rotated about a straight line then it seems to be identical to the original body or figure i.e., in any position of rotation the body or the figure is assumed to be the same, then the body or the figure is said to be Rotational Symmetrical body.
2. For example, when a circle is rotated with respect to its center, then no difference in the circle is observed.
3. So a circle is symmetrical with respect to its center.
4. Again when a top or a football is spinning about its axis, then in any position of this spinning its figure will be the same.
5. So the top of the football is symmetrical about its axis.

 

 

 

 

Triangle

 

Quadrilateral

 

 

Understanding Symmetry

Polygon

 

Dome English Capital Alphabets

 

 

Class 6 Math Solutions WBBSE English Medium

Some Figures Of Symmetrical Badies