ROTATIONAL SYMMETRY
Highlights of Presentaton:
Order of rotational symmetry
Centre of rotational symmetry
Angle of rotational symmetry
Examples of shapes
Presented by:
JYOTI SINGH
TGT Maths
KV Mughalsarai (Varanasi region)
Rotational Symmetry
An object is said to possess rotational symmetry when it looks exactly
the same after a rotation. The degree of rotational symmetry that an
object has is known as its order.
The order of rotational symmetry that an object has is the number of
times that it fits on to itself during a full rotation of 360 degrees.
Rotation turns the object about a fixed point which is know as centre of
rotation.
During rotation the angle at which the object attains its original
shape is called angle of rotation.
Rotational Symmetry
For shapes that have only “order 1” rotational symmetry a centre of
rotation can be found anywhere within it.
For shapes that have “order 2” rotational symmetry or
higher, a single centre of rotation can be located.
Order 1
Order 2
Order 3
Order 4
Rotational Symmetry
Order 1
The order of
rotational symmetry
that an object has is
the number of times
that it fits on to itself
during a full rotation
of 360 degrees.
Rotational Symmetry
Order 1
The order of
rotational symmetry
that an object has is
the number of times
that it fits on to itself
during a full rotation
of 360 degrees.
2
1
Order 2
Rotational Symmetry
Order 1
The order of
rotational symmetry
that an object has is
the number of times
that it fits on to itself
during a full rotation
of 360 degrees.
3
2
1
Order 3
2
1
Order 2
Rotational Symmetry
Order 1
The order of
rotational symmetry
that an object has is
the number of times
that it fits on to itself
during a full rotation
of 360 degrees.
3
2
2
1
Order 2
3
4
1
Order 3
2
Order 4
1
Rotational Symmetry
The figure attains its original shape at every turn of 120
degrees.This is the angle of rotation for given figure.
3
120
degrees
turn
2
120
degrees
turn
1
120
degrees
turn
Order 3
Rotational Symmetry
This figure attains its original shape four times during the complete
rotation each at an angle of 90 degrees .Angle of rotation is 90
degrees.
90 degrees
turn
90 degrees
turn
3
4
2
1
Order 4
90 degrees
turn
90 degrees
turn
NOW
EXAMPLES OF
ROTATIONAL
SYMMETRY FOR
POLYGONS
Equilateral Triangle
An equilateral triangle has rotational symmetry of order ?
Regular Polygons
Equilateral Triangle
An equilateral triangle has rotational symmetry of order ?
Equilateral Triangle
An equilateral triangle has rotational symmetry of order ?
3
2
1
3
Square
A square has rotational symmetry of order ?
Square
Square
A square has rotational symmetry of order ?
Square
4
A square has rotational symmetry of order ?
3
4
2
1
Regular Pentagon
A regular pentagon has rotational symmetry of order ?
Pentagon
Regular Pentagon
A regular pentagon has rotational symmetry of order ?
Regular Pentagon
A regular pentagon has rotational symmetry of order ?
5
4
1
3
2
5
Regular Hexagon
A regular hexagon has rotational symmetry of order ?
Hexagon
Regular Hexagon
A regular hexagon has rotational symmetry of order ?
Regular Hexagon
A regular hexagon has rotational symmetry of order ?
5
6
1
4
3
2
6
Regular Octagon
A regular octagon has rotational symmetry of order ?
Octagon
Regular Octagon
A regular octagon has rotational symmetry of order ?
7
8
6
1
5
2
4
3
8
Rectangle
A rectangle has rotational symmetry of order ?
Rectangle
Rectangle
A rectangle has rotational symmetry of order ?
2
2
1
Parallelogram
A parallelogram has rotational symmetry of order ?
Parallelogram
A parallelogram has rotational symmetry of order ?
2
2
1
Isosceles Triangle
An isosceles triangle has rotational symmetry of order ?
Isosceles Triangle
An isosceles triangle has rotational symmetry of order ?
1
1
Scalene Triangle
An scalene triangle has rotational symmetry of order ?
Scalene Triangle
An scalene triangle has rotational symmetry of order ?
1
1
Isosceles Trapezium
An isosceles trapezium has rotational symmetry of order ?
Isosceles Trapezium
An isosceles trapezium has rotational symmetry of order ? 1
1
Trapezium
A trapezium has rotational symmetry of order ?
Trapezium
A trapezium has rotational symmetry of order ?
1
1
Kite
A kite has rotational symmetry of order ?
Kite
A kite has rotational symmetry of order ?
1
1
Rhombus
A rhombus has rotational symmetry of order ?
Rhombus
A rhombus has rotational symmetry of order ?
2
2
1
Rotational Symmetry
State the order of rotational symmetry for each shape below:
1
2
3
Order 6
7
6
10
11
Questions 1
Order 4
8
Order 1
Order 5
Order 2
Order 3
Order 1
Order 2
Order 3
Order 2
5
9
4
12
Order 6
Order 8