Page 177 - New Medley 5 Semester 2

Observe the following rotations:

1 1 3
Original turn turn turn 1 full turn
4 2 4

or rotation or rotation or rotation or rotation
at 90° at 180° at 270° at 360°

The above figure rotates about a fixed point. It looks like the original

1
when rotated at turn or 180° angle and full turn or 360° angle. So it
2

is said to have rotational symmetry and its order of symmetry is 2.

Thus, when a figure is rotated through some angle in the clockwise or

anticlockwise direction and it looks like the original figure, it is said to
have rotational symmetry.

A square has the rotational symmetry of order 4. At every turn, it looks
like the original.

1 1 3
turn turn turn Full turn
4 2 4

An equilateral triangle has the rotational symmetry of order 3.

1 2
Original turn (120°) turn (240°) Full turn (360°)
3 3

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