Q.3 In the following figures, the mirror line (i.e., the line of symmetry) is given as a dotted line. Complete each figure performing reflection in the dotted (mirror) line. (You might perhaps place a mirror along the dotted line and look into the mirror for the image). Are you able to recall the name of the figure you complete?
NCERT Solutions for Class 7 Maths Chapter 14 Symmetry
Answer :
Q.4 The following figures have more than one line of symmetry. Such figures are said to have multiple lines of symmetry.
Identify multiple lines of symmetry, if any, in each of the following figures:
NCERT Solutions for Class 7 Maths Chapter 14 Symmetry
Answer :
Here, figure (a),(b), (c) , (d), (e), (g) and (h) are the multiple lines of symmetry.
Q.7 State the number of lines of symmetry for the following figures:
(?) An equilateral triangle
(b) An isosceles triangle
(c) A scalene triangle
(d) A square
(e) A rectangle
(f) A rhombus
(g) A parallelogram
(h) A quadrilateral
(i) A regular hexagon
(j) A circle
NCERT Solutions for Class 7 Maths Chapter 14 Symmetry
Answer :
(a) An equilateral triangle\(\rightarrow \) 3
(6) An isosceles triangle \(\rightarrow \) 1
(c) A scalene triangle \(\rightarrow \) 0
(d) A square \(\rightarrow \) 4
(e) A rectangle \(\rightarrow \) 2
(f) A rhombus \(\rightarrow \) 2
(g) A parallelogram \(\rightarrow \) 0
(h) A quadrilateral \(\rightarrow \) 0
(i) A regular hexagon \(\rightarrow \) 6
(j) A circle \(\rightarrow \) Infinite
Q. 8 What letters of the English alphabet have reflectional symmetry (i.e., symmetry related to mirror reflection) about.
(a) a vertical mirror
(b) a horizontal mirror
(c) both horizontal and vertical mirrors
NCERT Solutions for Class 7 Maths Chapter 14 Symmetry
Answer :
(a) Alphabet of vertical mirror reflection symmetry are
A, H, I, M, O, T, U, V, W, X, Y
(b) Alphabet of horizontal mirror reflection symmetry are:
B, C, D, E, H, I, K, O, X
(c) Alphabet of both horizontal and vertical mirror reflection symmetry are:
H, I, O, X.
NCERT Solutions for Class 7 Maths Chapter 14 Symmetry
Answer :
(a) Order of rotational symmetry = 360°/180°=2
(b) Order of rotational symmetry = 360°/180°=2
(C) Order of rotational symmetry = 360°/120°=3
(d) Order of rotational symmetry = 360°/90°=4
(e)Order of rotational symmetry = 360°/90°=4
(f) Order of rotational symmetry = 360°/72°=5
(g) Order of rotational symmetry = 360°/60°=5
(h) Order of rotational symmetry = 360°/120°=3
Q.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.
NCERT Solutions for Class 7 Maths Chapter 14 Symmetry
Answer :
(i) Equilateral triangle has 3 rotational symmetries.
(ii) A triangle with only line symmetry and no rotational symmetry of order more than 1 is isosceles triangle.
(iii) A quadrilateral with a rotational symmetry of order more than 1 but not a line symmetry is not possible to draw. Because, a quadrilateral with a line symmetry may have rotational symmetry of order one but not more than one.
(iv) A quadrilateral with line symmetry but not a rotational symmetry of order more than 1 is rhombus.