Page 200 - ICSE Math 7
P. 200
Line(s) of Symmetry of Geometrical Figures
A symmetrical figure can have more than one line of symmetry. Let’s find the lines of symmetry of
some geometrical figures.
(a) A line segment is symmetrical about its perpendicular bisector and the
line itself. Thus, a line segment has 2 lines of symmetry. A B
P
(b) An angle with equal arms is symmetrical about its bisector and hence
has 1 line of symmetry.
Q R
P
(c) An isosceles triangle is symmetrical about the angle bisector of the
angle formed by its equal sides. Thus, an isosceles triangle has only
1 line of symmetry.
Q R
P
(d) An equilateral triangle is symmetrical about the angle bisectors of its
three vertices which are also the perpendicular bisectors of its sides.
Thus, an equilateral triangle has 3 lines of symmetry.
Q R
S R
(e) A rectangle is symmetrical about the perpendicular bisectors of its
two adjacent sides. Thus, a rectangle has 2 lines of symmetry.
P Q
S R
(f) A square is symmetrical about the perpendicular bisectors of its two
adjacent sides and two diagonals. Thus, it has 4 lines of symmetry.
Q
P
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