Page 201 - ICSE Math 7

S R
(g) A rhombus is symmetrical about its two diagonals. Thus, it has
2 lines of symmetry.

P Q

(h) A trapezium has no line of symmetry but an isosceles trapezium S R
is symmetrical about the line joining the midpoints of its parallel
sides. Thus, an isosceles trapezium has 1 line of symmetry.
P Q

P

(i) A kite is symmetrical along its one diagonal. Thus, it has 1 line of Q S
symmetry.

R

(j) A circle is symmetrical about any line passing through its centre.
Thus, a circle has infinite lines of symmetry. O

(k) A semicircle is symmetrical about the perpendicular bisector of
the diameter. Thus, it has 1 line of symmetry.

P Q

A
(l) An arrowhead has only 1 line of symmetry as shown in the
adjoining figure.

C
B D
Example 1: For each of the following letters, find the number of lines of symmetry.

(a) (b) (c) (d)

Solution: (a) ; 1 vertical line of symmetry

(b) ; 1 vertical and 1 horizontal, thus 2 lines of symmetry

(c) ; 1 horizontal line of symmetry

(d) ; 1 vertical line of symmetry

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