S.chand publication New Learning Composite mathematics solution of class 7 Chapter 12 Reflection and Rotation Symmetry Exercise 12C

 Exercise 12C

Question 1

Which of the following figures have a rotational symmetry about the marked point?

(a) Yes

(b) Yes

(c) Yes

(d) Yes

(e) No

(f) Yes

(g) Yes

(h) No

Question 2

Complete each figure.The marked point is the centre of rotation and the order rotational symmetry for each figure is given.

(a) Figure to be added

(b) Figure to be added

(c) Figure to be added

(d) Figure to be added

(e) Figure to be added

(f) Figure to be added

(g) Figure to be added

(h) Figure to be added

Question 3

State the order of rotational symmetry of the following shapes

(a) 3

(b) 2

(c) 4

(d) 5

(e) 7

(f) 4

(g) 2

(h) 4

Question 4

Find the order of rotational symmetry of these flower beads by tracing them

(a) 3

(b) 1

Question 5

Work out the order of rotational symmetry for each shape. Use tracing paper if you need to 

(a) 2

(b) 6

(c) 3

(d) 3

(e) 2

Question 6

Fill in the blanks

Shape	Centre of rotation	Order of rotation	Angle of rotation
Square	Point of intersection of the line segment joining the mid-points of opposite sides	4	90°
Rectangle	Point of intersection of the line segment joining the mid-points of opposite sides	2	180°
Rhombus	Point of intersection of angle bisector i.e. centroid	2	180°
Equilateral	Center of the hexagon	3	120°
Regular hexagon	Centre of the hexagon	6	60°
Circle	Center of the circle	Infinite	Any angle
Semi circle	Nil	Nil	Nil

Question 7

English alphabet Letter	Line symmetry	Number of lines of symmetry	Rotational symmetry	Order of Rotational symmetry
Z	No	0	Yes	2
S	No	0	Yes	2
H	Yes	2	Yes	2
O	Yes	Infinite	Yes	2
E	Yes	1	No	0
N	No	0	Yes	2
C	Yes	1	No	0

Question 8

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

(a) 45° (b) 17°

Sol :

(a) Yes, 360° is exactly divisible by 45°

(b) No, 360° is not divisible by 17°

Question 9

Given figure is a part of a shape with center of rotation O. The order of rotational symmetry is 6. Complete the figure.

Figure to be  added