5 February 2014

About Rotational Symmetry

  • Any object or shape is said to have rotational symmetry if it looks exactly the same at least once during a complete rotation through three hundred and sixty degrees.
  • During the rotation, the object rotates around a fixed point. Its shape and size do not change.
  • This fixed point is called the centre of rotation.
  • Rotation may be clockwise or anti-clockwise.
  • A full turn refers to a rotation of three hundred and sixty degrees.
  • A half turn refers to a rotation of one hundred and eighty degrees.
  • A quarter turn refers to a rotation of ninety degrees.
  • The angle at which a shape or an object looks exactly the same during rotation is called the angle of rotation.
  • The order of rotational symmetry can be defined as the number of times that a shape appears exactly the same during a full 360rotation.
Rotation,  Rotational symmetry, Complete rotation, Fixed point, Centre of rotation,
Clockwise, anticlockwise,  Angle of rotation, Order of rotational symmetry
  • The centre of rotation of a square is its centre. The angle of rotation of a square is 90 degrees, and its order of rotational symmetry is 4.
Centre of rotation, Angle of rotation, Order of the rotational symmetry
  • The centre of rotation of a circle is the centre of the circle.
Centre of rotation, Centre of the circle, Infinite lines of symmetry
  • There are many shapes that have only line symmetry and no rotational symmetry at all.
  • Some objects and shapes have both, line symmetry as well as rotational symmetry.
  • The Ashok Chakra in the Indian national flag has both, line symmetry and rotational symmetry.
Line symmetry, Rotational symmetry
  • Symmetry can be seen in the English alphabet as well.
  • The letter H has both line symmetry and rotational symmetry.
Symmetry ,Line symmetry, Rotational symmetry

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