CBSE students can refer to NCERT Solutions for Class 7 Maths Chapter 14 Symmetry Ex 14.2 Textbook Questions and Answers are provided by experts in order to help students secure good marks in exams.
Class 7 Maths NCERT Solutions Chapter 14 Symmetry Ex 14.2
Question 1.
Which of the following figures have rotational symmetry of order more than 1:
(a)
(b)
(c)
(d)
(e)
(f)
Solution:
Figures (a), (b), (d), (e), and (f) have rotational symmetry of order more than 1.
Question 2.
Give the order of rotational symmetry for each figure :
(a)
Solution:
Let us mark a point A on each figure and also indicate the angle through which the figure is to be rotated as under :
(b)
Solution:
Let us mark a point A on each figure and also indicate the angle through which the figure is to be rotated as under :
(c)
Solution:
Let us mark a point A on each figure and also indicate the angle through which the figure is to be rotated as under :
(d)
Solution:
Let us mark a point A on each figure and also indicate the angle through which the figure is to be rotated as under :
(e)
Solution:
Let us mark a point A on each figure and also indicate the angle through which the figure is to be rotated as under :
(f)
Solution:
Let us mark a point A on each figure and also indicate the angle through which the figure is to be rotated as under :
(g)
Solution:
Let us mark a point A on each figure and also indicate the angle through which the figure is to be rotated as under :
(h)
Solution:
Let us mark a point A on each figure and also indicate the angle through which the figure is to be rotated as under :
Now to find the rotational symmetry, we proceed as under :
In figure (a): it requires two rotations, each through an angle of 180°, about the marked point (x) to come back to its original position. So, its rotational symmetry is of order 2.
In figure (b): It requires two rotations, each through an angle of 180°, about the marked point (x) to come back to its original position. So, its rotational symmetry is of order 2.
In figure (c): The triangle requires three rotations, each through an angle of 120° about the marked point to come back to its original position. So, it has rotational symmetry of order 3.
In figure (d): The figure requires four rotations, each through an angle of 90°, about the marked point (x) to come back to its original position. So, its rotational symmetry is of order 4.
n figure (e): The figure requires four rotations, each through an angle of 90°, about the marked point (x) to come back to its original position. So, its rotational symmetry is of order 4.
In figure (f): The regular pentagon requires five rotations, each through an angle of 72°, about the marked point to come back to its original position. So, it has rotational symmetry of order 5.
In figure (g): The figure requires six rotations, each through an angle of 60°, about the marked point to come back to its original position. So, it has rotational symmetry of order 6.
In figure (h): The figure requires three rotations each through an angle of 120°, about the marked point to come back to its original position. So, it has rotational symmetry of order 3.