Line Symmetry

Line symmetry is discussed here. We know that any object or shape which can be cut in two equal halves in such a way that both the parts are exactly the same is called symmetrical and the line which divides the shape in two equal halves is called the line of symmetry. A shape can have many lines of symmetry.

Let us follow some of the pictures or figures given below.

(i) Examples of vertical lines of symmetry:

$Vertical Lines of Symmetry$

Vertical Lines of Symmetry

(ii) Examples of horizontal lines of symmetry:

$Horizontal Lines of Symmetry$

Horizontal Lines of Symmetry

Each is divided by a straight line. Both the parts are equal in all respects. When the pictures or figures are folded along the straight lines, one part will fit or cover the other part exactly.

Such pictures or figures of which either of the two parts made by a straight line, covers the other part exactly when folded along this line, are called symmetrical figures. The straight lines are called the lines of symmetry of the respective figures. In the above pictures or figures the lines of symmetry are both horizontal and vertical.

$Horizontal and Vertical Lines of Symmetry$

In the above figure the straight lines shown are not lines of symmetry.

Let us consider some of the symmetrical figures which have been folded along the lines of symmetry:

(i)

$Symmetrical Figures$

(ii)

$Examples of Symmetrical Figures$

These are the basic and main points to understand line symmetry.

Questions and Answers on Line Symmetry:

1. Choose the right answer.

(i) The number of lines of symmetry in a regular pentagon are:

(a) 3

(b) 4

(d) 6

(ii) The number of lines of symmetry in an isosceles triangle:

(a) 1

(b) 2

(d) 4

Answer:

(i) (c)

(ii) (c)

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