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.

#### Class 7 Maths Chapter 12 Exercise 12.2 Solution in Videos

#### 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.

### Class 7 Maths Exercise 12.2 Important Questions

### 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.