WBBSE Solutions For Class 7 Maths Geometry Chapter 9 Symmetry

Geometry Chapter 9 Symmetry

Question 1. Choose the correct answer.

1. The number of lines of symmetry of a square

1. 1
2. 2
3. 3
4. 4

∴ The option(4) 4 is the correct answer.

2. The number of lines symmetry of a circle is

1. 2
2. 3
3. 4
4. Infinite

∴ The option (4) Infinite is the correct answer.

3. There is no centre of rotation of

1. Circle
2. Rhombus
3. Isosceles trapezium
4. Equilateral triangle

∴ The option (3) Isosceles trapezium is correct answer

Read and Learn More Class 7 Maths Solutions

4. In which Figure has no line of symmetry

1. H
2. P
3. T
4. X

∴ The option (2) P is the correct answer.

Class 7 Geometry Chapter 9 Exercise Solutions

5. In which Figure has a line of symmetry and rotational symmetry both?

1. Isosceles triangle.
2. Isosceles trapezium
3. Circle
4. Parallelogram.

∴ The option (3) Circle is the correct answer

Question 2. write true or False:

1. Isosceles triangle has no line of symmetry → True

2. The number of rotational symmetry of the circle is ‘2’ → False

3. The angle of rotation of the rectangle is 90°→ False

4. The order of rotational Symmetry of a square is 4. → True

5. The largest number of lines of symmetry of a triangle is 3 → True.

Class 7 Maths Chapter 9 Geometry PDF

Question 3. Fill in the blanks:-

1. Trapezium has no Line of symmetry or rotational Symmetry

2. The number of lines of Symmetry of a regular Pentagon is  1

3. The number of lines of symmetry of an isosceles right-angled triangle is 1

4. The angle of rotation symmetry of a parallelogram is 180°

5. ______ triangle has only one line of Symmetry. Isosceles

Question 4. Which of the following figures has two lines of Symmetry and the angles or rotational symmetry is 180°
Solution:

→ Rectangle has two lines of Symmetry and angles or rotational symmetry is 180°

→ Parallelogram has no axis of Symmetry

→ It has No Angle of rotational symmetry.

→ Isosceles trapezium has 1 line of Symmetry.

→ It has No Angle of rotational symmetry

→ Square has 4 lines of symmetry

→ Angle of rotational Symmetry is +90°

Class 7 Geometry Chapter 9 Important Questions

Question 5.

1. what is symmetry?
Solution:

→Symmetry means an exact similarity in shape and size between parts of an object of a figure.

2. what is a line of symmetry?
Solution:

A figure is said to be a line of Symmetry of linear symmetry of these exists a straight line that divides into two identical halves that completely coincide with each other when folded about that line.

The straight line is called the line of symmetry of the line of reflection

3. what is rotational symmetry?
Solution:

→ In a Figure that coincides with its images when it is rotated about a point through an angle less than 360° the Figure is said to be rotational Symmetry.

The point across which the Figure rotates is called the center of rotation.

WBBSE Class 7 Maths Geometry Chapter 9 

4. what is the angle of rotational symmetry?
Solution:

For a Figure or object that has rotational symmetry the angle of turning during rotation is called the angle of rotation.

For Example: when a square is rotated by qo’ it appears the same after rotation. So the angle of rotation of the Square is 90°

Question 6. Find the angles of rotation of the following.

1. Trapezium
2. Rhombus
3. Equilateral triangle

Solution:

1. Trapezium has No out angle of rotation.
2. The rhombus has a 180° out angle of rotation.
3. An equilateral triangle has a 120° out angle of rotation