Does It Look The Same

Does It Look The Same ? | Class 5 | Mathematics |  NCERT SOLUTIONS

Mirror halves

Which figures are called mirror halves ?

The figures which are mirror images of each other are called mirror halves.

Example

In figure 1 the left side part is the mirror image of right side part. Both of the parts are identical in all respect. So the two parts are mirror halves.

In figure 2 the left side part is not the mirror image of the right side part. Both the parts are not identical in all respect. So the two parts are not mirror halves.

In figure 3 the top part is not the mirror image of the bottom part. Both the parts are not identical in all respect due to colour mismatch. So the two parts are not mirror halves.

Symmetrical Figures

The figures which are mirror halves are called symmetric figures.

For example

 Asymmetrical figures

The figures which are not mirror halves are called asymmetric figures.

For example

Line of Symmetry

The  line which divides a figure into two mirror halves is called as line of symmetry.

For example

Activity 1

1. Draw two symmetrical figures.

2. Draw two asymmetrical figures.

3. Paste two objects which can be divided into two symmetrical figures.

4. Draw a figure and show the line of symmetry.

5. Paste two objects which can not be divided into two symmetrical figures.

Rotational Symmetry

Q. What is rotational symmetry ?

A figure when looks exactly same after rotating around a fixed point is called rotational symmetry.

Example:

A rectangle when rotates 180 degree it looks same.

So we can say a rectangle shows rotational symmetry at an angle of 180 degree.

         

      

A square when rotates 90 degree it looks same.

So we can say a square shows rotational symmetry at an angle of 90 degree.

Q. Write the measurements when an object takes the following turns.

( Remember 1 complete rotation = 360 degree )

Number of turns	Angle measurement in degrees
Complete turn	360˚
Half a turn	180˚
Quarter turn or One-fourth turn	90˚
Three-fourth turn	270˚
One-third turn	120˚
One-sixth turn	60˚
One-eighth turn	45˚