rotational symmetry highlights of presentaton: order of rotational symmetry centre of rotational...
TRANSCRIPT
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.
During rotation the angle at which the object attains its original shape is called angle of rotation.
Rotation turns the object about a fixed point which is know as centre of rotation.
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 Order 2 Order 3 Order 4
For shapes that have “order 2” rotational symmetry or higher, a single centre of rotation can be located.
For shapes that have only “order 1” rotational symmetry a centre of rotation can be found anywhere within it.
Rotational SymmetryThe 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.
Order 1
Rotational Symmetry
Order 11
2
Order 2
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 11
2
Order 2
12
3
Order 3
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 11
2
Order 2
12
3
Order 312
3 4
Order 4
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
12
3
Order 3
The figure attains its original shape at every turn of 120 degrees.This is the angle of rotation for given figure.
120 degrees turn
120 degrees turn
120 degrees turn
Rotational Symmetry
12
3 4
Order 4
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
90 degrees turn
90 degrees turn
NOW EXAMPLES OF ROTATIONAL SYMMETRY FOR POLYGONS
Equilateral Triangle
An equilateral triangle has rotational symmetry of order ?
Regular PolygonsRegular Polygons
Equilateral Triangle
An equilateral triangle has rotational symmetry of order ?
Equilateral Triangle
An equilateral triangle has rotational symmetry of order ?
12
33
Square
A square has rotational symmetry of order ?
SquareSquare
Square
A square has rotational symmetry of order ?
Square
A square has rotational symmetry of order ?
12
3
4
4
PentagonPentagon
Regular Pentagon
A regular pentagon has rotational symmetry of order ?
Regular Pentagon
A regular pentagon has rotational symmetry of order ?
Regular Pentagon
A regular pentagon has rotational symmetry of order ? 5
1
23
4
5
HexagonHexagon
Regular HexagonA regular hexagon has rotational symmetry of order ?
Regular HexagonA regular hexagon has rotational symmetry of order ?
1
23
4
5 6
Regular HexagonA regular hexagon has rotational symmetry of order ? 6
Regular OctagonA regular octagon has rotational symmetry of order ?
OctagonOctagon
1
2
34
5
6
Regular OctagonA regular octagon has rotational symmetry of order ? 8
7 8
RectangleRectangle
RectangleA rectangle has rotational symmetry of order ?
2
1
2
RectangleA rectangle has rotational symmetry of order ?
ParallelogramA parallelogram has rotational symmetry of order ?
2
1
2
ParallelogramA parallelogram has rotational symmetry of order ?
Isosceles TriangleAn isosceles triangle has rotational symmetry of order ?
1
1
Isosceles TriangleAn isosceles triangle has rotational symmetry of order ?
Scalene TriangleAn scalene triangle has rotational symmetry of order ?
1
1
Scalene TriangleAn scalene triangle has rotational symmetry of order ?
Isosceles TrapeziumAn isosceles trapezium has rotational symmetry of order ?
1
1
Isosceles TrapeziumAn isosceles trapezium has rotational symmetry of order ?
TrapeziumA trapezium has rotational symmetry of order ?
1
1
A trapezium has rotational symmetry of order ?
Trapezium
A kite has rotational symmetry of order ?
Kite
1
1
A kite has rotational symmetry of order ?
Kite
A rhombus has rotational symmetry of order ?
Rhombus
2
1
A rhombus has rotational symmetry of order ?
Rhombus
2
Questions 1Questions 1
Rotational SymmetryState the order of rotational symmetry for each shape below:
1 2 3 4
5 6 7 8
9 10 11 12
Order 6 Order 2 Order 3 Order 2
Order 1 Order 3 Order 2 Order 5
Order 4 Order 1 Order 6 Order 8