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CBSE - VII
Rotational Symmetry
Rotational Symmetry
Any object or shape is said to have rotational symmetry if it looks exactly the same...
Lesson Demo
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 360orotation.
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.
