- 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 360o rotation.
- 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.
- The centre of rotation of a circle is the centre of the circle.
- 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.
- Symmetry can be seen in the English alphabet as well.
- The letter H has both line symmetry and rotational symmetry.
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