NCERT Solutions(Part - 2) - Symmetry Class 7 Notes | EduRev

Mathematics (Maths) Class 7

Created by: Praveen Kumar

Class 7 : NCERT Solutions(Part - 2) - Symmetry Class 7 Notes | EduRev

The document NCERT Solutions(Part - 2) - Symmetry Class 7 Notes | EduRev is a part of the Class 7 Course Mathematics (Maths) Class 7.
All you need of Class 7 at this link: Class 7

Exercise 14.3 

Question 1: 

Name any two figures that have both line symmetry and rotational symmetry. 

Answer 1: 

Circle and Square.

Question 2: 

Draw, wherever possible, a rough sketch of: 

(i) a triangle with both line and rotational symmetries of order more than 1. 

(ii) a triangle with only line symmetry and no rotational symmetry of order more than 1. 

(iii) a quadrilateral with a rotational symmetry of order more than 1 but not a line symmetry. 

(iv) a quadrilateral with line symmetry but not a rotational symmetry of order more than 1. 

Answer 2: 

(i) An equilateral triangle has both line and rotational symmetries of order more than 1.

Line symmetry:

NCERT Solutions(Part - 2) - Symmetry Class 7 Notes | EduRev

Rotational symmetry:

NCERT Solutions(Part - 2) - Symmetry Class 7 Notes | EduRevNCERT Solutions(Part - 2) - Symmetry Class 7 Notes | EduRevNCERT Solutions(Part - 2) - Symmetry Class 7 Notes | EduRev

(ii) An isosceles triangle has only one line of symmetry and no rotational symmetry of order more than 1.

Line symmetry:

NCERT Solutions(Part - 2) - Symmetry Class 7 Notes | EduRev

Rotational symmetry:

NCERT Solutions(Part - 2) - Symmetry Class 7 Notes | EduRev

(iii) It is not possible because order of rotational symmetry is more than 1 of a figure, most acertain the line of symmetry.

(iv) A trapezium which has equal non-parallel sides, a quadrilateral with line symmetry but not a rotational symmetry of order more than 1. 

Line symmetry: 

NCERT Solutions(Part - 2) - Symmetry Class 7 Notes | EduRev

Rotational symmetry: 

NCERT Solutions(Part - 2) - Symmetry Class 7 Notes | EduRev

Question 3: 

In a figure has two or more lines of symmetry, should it have rotational symmetry of order more than 1? 

Answer 3: 

Yes, because every line through the centre forms a line of symmetry and it has rotational symmetry around the centre for every angle.

 

Question 4: 

Fill in the blanks: 

 

Shape

Centre of Rotation

Order of Rotation

Angle of Rotation

Square

 

 

 

Rectangle

 

 

 

Rhombus

 

 

 

Equilateral triangle

 

 

 

Regular hexagon

 

 

 

Circle

 

 

 
Semi-circle   

 

Answer 4: 

Shape

Centre of Rotation

Order of Rotation

Angle of Rotation

Square

Intersecting point of diagonals.

4

90°

Rectangle

Intersecting point of diagonals.

2

180°

Rhombus

Intersecting point of diagonals.

2

180°

Equilateral

triangle

Intersecting point of medians.

3

120°

Regular

hexagon

Intersecting point of diagonals.

6

60°

Circle

Centre

infinite

At every point

Semi-circle

Mid-point of diameter

1

360°

 

Question 5: 

Name the quadrilateral which has both line and rotational symmetry of order more than 1. 

Answer 5: 

Square has both line and rotational symmetry of order more than 1.

Line symmetry:  NCERT Solutions(Part - 2) - Symmetry Class 7 Notes | EduRev

Rotational symmetry:

NCERT Solutions(Part - 2) - Symmetry Class 7 Notes | EduRevNCERT Solutions(Part - 2) - Symmetry Class 7 Notes | EduRev

Question 6: 

After rotating by 60o about a centre, a figure looks exactly the same as its original position. At what other angles will this happen for the figure? 

Answer 6: 

Other angles will be 120°, 180°,240°,300°,360°.

For 60° rotation:

It will rotate six times.

NCERT Solutions(Part - 2) - Symmetry Class 7 Notes | EduRevNCERT Solutions(Part - 2) - Symmetry Class 7 Notes | EduRevNCERT Solutions(Part - 2) - Symmetry Class 7 Notes | EduRev

NCERT Solutions(Part - 2) - Symmetry Class 7 Notes | EduRevNCERT Solutions(Part - 2) - Symmetry Class 7 Notes | EduRevNCERT Solutions(Part - 2) - Symmetry Class 7 Notes | EduRev

For 120° rotation:

It will rotate three times.

NCERT Solutions(Part - 2) - Symmetry Class 7 Notes | EduRevNCERT Solutions(Part - 2) - Symmetry Class 7 Notes | EduRevNCERT Solutions(Part - 2) - Symmetry Class 7 Notes | EduRev

For 180° rotation:

It will rotate two times.

NCERT Solutions(Part - 2) - Symmetry Class 7 Notes | EduRev

For 360° rotation:

It will rotate one time.

NCERT Solutions(Part - 2) - Symmetry Class 7 Notes | EduRev

Question 7: 

Can we have a rotational symmetry of order more than 1 whose angle of rotation is: 

(i) 45o 
(ii) 17o

Answer 7: 

(i) If tiie angle of rotation is 45°, then symmetry of order is possible and would be 8 rotations.
(ii) If the angle of rotational is 17°, then symmetry o f order is not possible because 360° is not complete divided by 17°.

Offer running on EduRev: Apply code STAYHOME200 to get INR 200 off on our premium plan EduRev Infinity!

Complete Syllabus of Class 7

Dynamic Test

Content Category

Related Searches

Sample Paper

,

Extra Questions

,

Free

,

Semester Notes

,

Summary

,

NCERT Solutions(Part - 2) - Symmetry Class 7 Notes | EduRev

,

pdf

,

video lectures

,

NCERT Solutions(Part - 2) - Symmetry Class 7 Notes | EduRev

,

study material

,

Previous Year Questions with Solutions

,

Important questions

,

NCERT Solutions(Part - 2) - Symmetry Class 7 Notes | EduRev

,

mock tests for examination

,

ppt

,

Exam

,

practice quizzes

,

Objective type Questions

,

shortcuts and tricks

,

MCQs

,

past year papers

,

Viva Questions

;