RD Sharma Class 7 ex 18.3 Solutions Chapter 18 Symmetry

In this chapter, we provide RD Sharma Class 7 ex 18.3 Solutions Chapter 18 Symmetry for English medium students, Which will very helpful for every student in their exams. Students can download the latest RD Sharma Class 7 ex 18.3 Solutions Chapter 18 Symmetry Maths pdf, Now you will get step by step solution to each question.

TextbookNCERT
ClassClass 7
SubjectMaths
ChapterChapter 18
Chapter NameSymmetry
ExerciseEx 18.3

RD Sharma Solutions for Class 7 Chapter 18 Symmetry Ex 18.3 Download PDF

Chapter 18 Symmetry Exercise 18.3

Question: 1

Give the order of rotational symmetry for each of the following figures when rotated about the marked point (x):

Chapter 18 Symmetry Exercise 18.3 Question 1

Solution:

(i) The given figure has its rotational symmetry as 4.

(ii) The given figure has its rotational symmetry as 3.

(iii) The given figure has its rotational symmetry as 3.

(iv) The given figure has its rotational symmetry as 4.

(v) The given figure has its rotational symmetry as 2.

(vi) The given figure has its rotational symmetry as 4.

(vii) The given figure has its rotational symmetry as 5.

(viii) The given figure has its rotational symmetry as 6.

(ix) The given figure has its rotational symmetry as 3.

Question: 2

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

Solution:

An equilateral triangle and a square have both lines of symmetry and rotational symmetry.

Chapter 18 Symmetry Exercise 18.3 Question 2

Question: 3

Give an example of a figure that has a line of symmetry but does not have rotational symmetry.

Solution:

A semicircle and an isosceles triangle have a line of symmetry but do not have rotational symmetry.

Chapter 18 Symmetry Exercise 18.3 Question 3

Question: 4

Give an example of a geometrical figure which has neither a line of symmetry nor a rotational symmetry.

Solution:

A scalene triangle has neither a line of symmetry nor a rotational symmetry.

Chapter 18 Symmetry Exercise 18.3 Question 4

Question: 5

Give an example of a letter of the English alphabet which has

(i) No line of symmetry

(ii) Rotational symmetry of order 2.

Solution:

(i) The letter of the English alphabet which has no line of symmetry is Z.

(ii) The letter of the English alphabet which has rotational symmetry of order 2 is N.

Question: 6

What is the line of symmetry of a semi-circle? Does it have rotational symmetry?

Solution:

A semicircle (half of a circle) has only one line of symmetry. In the figure, there is one line of symmetry. The figure is symmetric along the perpendicular bisector I of the diameter XY.

A semi-circle does not have any rotational symmetry.

Chapter 18 Symmetry Exercise 18.3 Question 6

Question: 7

Draw, whenever possible, a rough sketch of

(i) a triangle with both line and rotational symmetries.

(ii) a triangle with only line symmetry and no rotational symmetry.

(iii) a quadrilateral with a rotational symmetry but not a line of symmetry.

(iv) a quadrilateral with line symmetry but not a rotational symmetry.

Solution:

(i) An equilateral triangle has 3 lines of symmetry and a rotational symmetry of order 3.

Chapter 18 Symmetry Exercise 18.3 Question 7a

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

Chapter 18 Symmetry Exercise 18.3 Question 7b

(iii) A parallelogram is a quadrilateral which has no line of symmetry but a rotational symmetry of order 2.

Chapter 18 Symmetry Exercise 18.3 Question 7c

(iv) A kite is a quadrilateral which has only one line of symmetry and no rotational symmetry.

Chapter 18 Symmetry Exercise 18.3 Question 7d

Question: 8

Fill in the blanks:

FiguresCentre of rotationOrder of rotationAngle of rotation  
Square   
Rectangle   
Rhombus   
Equilateral triangle   
Regular hexagon   
Circle   
Semi-circle   

Solution:

FiguresCentre of rotationOrder of rotationAngle of rotation  (°)
SquarePoint of intersection of the line segments joining the mid-points of opposite sides.490
RectanglePoint of intersection of the line segments joining the mid-points of opposite sides2180
RhombusPoint of intersection of diagonals2180
Equilateral trianglePoint of intersection of angle bisectors i.e, centroid3120
Regular hexagonCentre of the hexagon660
CircleCentre of the circleUnlimitedAny angle
Semi-circleNilNILNil

 

Question: 9

Fill in the blanks:

English alphabet LetterLine SymmetryNumber of Lines of symmetryRotational SymmetryOrder of rotational Symmetry
ZNil0YES2
S
HYESYES
OYESYES
EYES
NYES
C

Solution:

English alphabet LetterLine SymmetryNumber of Lines of symmetryRotational SymmetryOrder of rotational Symmetry
ZNO0YES2
SNO0YES2
HYES2YES2
OYES4YES2
EYES1NO0
NNO0YES2
CYES1NO0

All Chapter RD Sharma Solutions For Class 7 Maths

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