Page 252 - Start Up Mathematics_6

RefIection and Symmetry
If we see the image of any object in a mirror,
then the object and its mirror image are
symmetrical in reference to the mirror line.
If the paper is folded along the mirror line,
the mirror line becomes the line of symmetry.
The image is a reflection of the object in the
line of symmetry. When a figure is reflected
about a line, the image is congruent to the object mirror image
original figure, i.e., the lengths and angles
of the image are equal to the corresponding
lengths and angles of the original figure. However, in one aspect there is a change in the image
and the object. The image of the object is laterally inverted.
One can collect objects like leaves, kite, stamps, etc. or geometrical figures like circle, rectangle
(e.g. coin or postcard), etc. and check them for reflection symmetry using a mirror.
Example 13: Find the number of lines of symmetry in each of the following shapes. How will
you check your answers?

(a) (b) (c)

(d) (e) (f)

Solution: (a) (b) (c)

(1 line) (1 line) (2 lines)

(d) (e) (f)

(1 line) (1 line) (2 lines)

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