Chapter 13 Symmetry

Question 1.
Write four such English letters which have no line of symmetry.
Solution:
The 4 English letters having no line of symmetry are: P, F, G and Z.

Question 2.
Write 5 such English letters which have horizontal line of symmetry.
Solution:
The required letters are:
E, B, C, D,K

Question 3.
Write 4 English letters which have vertical lines of symmetry.
Solution:
The required English letters are A, H, I, M

Question 4.
How many symmetrical lines do they have?

Solution:
(a) The figure is a square. It has 4 lines of symmetry.

(b) It is an isosceles triangle. It has one vertical line of symmetry.

(c) The given figure is a rectangle which has two lines of symmetry.

Question 5.
Find in which of the following, the dotted line is a line of symmetry.

Solution:
(a) The dotted line is a line of symmetry.
(b) The dotted line is a line of symmetry.
(c) The dotted line is not a line of symmetry.
(d) The dotted line is not a line of symmetry.
(e) The dotted line is a line of symmetry.
(f) The dotted line is a line of symmetry.

Question 6.
How many lines of symmetry does (a) a rectangle (b) a square (c) a parallelogram have? What about right angled triangle?
Solution:
(a) Rectangle has two lines of symmetry
(i) Horizontal
(ii) Vertical

(b) Square has four lines of symmetry.
(i) 1 horizontal
(ii) 1 vertical
(iii) 2 diagonally

(c) Parallelogram has no lines of symmetry

Right angled triangle has no line of symmetry.

Question 7.
Fill in the blanks:
(a) An angle is symmetrical about its …….. .
(b) A circle has …….. lines of symmetry.
(c) A rectangle …….. has lines of symmetry.
(d) A square has …….. lines of symmetry.
(e) A letter D has …….. lines of symmetry.
(f) A letter N has …….. lines of symmetry.
(g) A kite is symmetrical about its longer …….. .
(h) A scalene triangle has …….. lines of symmetry.
(i) A line of symmetry of an object is also called its …….. of symmetry.
(j) An equilateral triangle has …….. lines of symmetry.
(k) A regular pentagon has …….. lines of symmetry.
(l) A line of …….. divides a figure into two similar parts.
Solution:
(a) bisector
(b) infinite
(c) two
(d) four
(e) one
(f) no
(g) diagonal
(h) no
(i) axis
(j) three
(k) five
(l) symmetry

Question 8.
Show by figure the English alphabets which look the same in their reflected image.
Solution:
The following English alphabets look same after reflections.