 NCERT Solutions for Class 7 Maths Chapter 12 Exercise 12.2 Symmetry in Hindi and English Medium for CBSE session 2023-24. Students of class VII can get the revised solutions of ex. 12.2 mathematics here based on new syllabus and latest textbooks issued for academic year 2023-24.

• ## Class 7 Maths Exercise 12.2 Solution in Hindi and English Medium

 Class: 7 Mathematics Chapter: 12 Exercise: 12.2 Chapter Name: Symmetry Content Mode: Images, Text and Videos Academic Session: CBSE 2023-24 Medium: English and Hindi Medium

### Class 7 Maths Chapter 12 Exercise 12.2 Solution

All the contents are updated according to latest CBSE syllabus 2023-24. In class 7 math NCERT exercise 12.2 the concepts are given based on rotational symmetry. Here the questions are simple but somehow tricky. Student need more attention to do these questions.

#### Rotational Symmetry

Rotation means the circular movement of an object around a center. It is possible to rotate different shapes by an angle around the center point.

Examples:
If you spin the wheel of a bicycle, it rotates. It can rotate in either way: both clockwise and anticlockwise.
(i) a clockwise rotation and
(ii) anticlockwise rotation.

### How do you know if a shape has rotational symmetry?

A figure has rotational symmetry if it can be rotated by an angle between 0° and 360° so that the image coincides with the pre-image. The angle of rotational symmetry is the smallest angle for which the figure can be rotated to coincide with itself.

### Which figure has only rotational symmetry?

Common figures with only rotational symmetry are the recycling sign and fan blades. If a figure coincides with the original twice in one full turn, it has two-fold rotational symmetry, or rotational symmetry order two.

### What are the 4 types of symmetry?

The four main types of this symmetry are:
(i) Translation
(ii) Rotation
(iii) Reflection
(iv) Glide reflection.

### Do parallelograms have rotational symmetry?

Parallelogram. A parallelogram has no lines of symmetry. It has rotational symmetry of order two.

#### Centre of Rotation

When an object rotates, its shape and size do not change. The rotation turns an object about a fixed point. This fixed point is the centre of rotation.

##### Angle of Rotation

The angle of turning during rotation is called the angle of rotation. A full turn, you know, means a rotation of 360°.
Example:
The degree measure of the angle of rotation for
(i) a half-turn is 180⁰
(ii) a quarter-turn is 90⁰

###### Order of Rotational Symmetry

Consider a square with P as one of its corners
Let us perform quarter-turns about the centre of the square marked x. Rotation by 90° about the centre. In this way, when you complete four quarter-turns, the square reaches its original position.

Thus a square has a rotational symmetry of order 4 about its centre. Observe that in this case,
(i) The centre of rotation is the centre of the square.
(ii) The angle of rotation is 90°.
(iii) The direction of rotation is clockwise.
(iv) The order of rotational symmetry is 4.   Last Edited: April 21, 2023