presentation on symmetry and rotational symmetry..

1. Math's holiday
homework
symmetry

2.  Symmetry generally conveys two primary
meanings. The first is an imprecise sense of
harmonious or aesthetically pleasing
proportionality and balance; such that it reflects
beauty or perfection. The second meaning is a
precise and well-defined concept of balance or
"patterned self-similarity" that can be
demonstrated or proved according to the rules of
a formal system: by geometry, through physics or
otherwise.

4.  An equilateral triangle is regular because each of its sides has same
lengths and each of its angles measure 60°.
A square is also regular because all its sides are of equal lengths
and each of its angle is a right angle (i.e.90 °). Its diagonals are
seem to be perpendicular bisectors of one another.

5.  If pentagon is regular, naturally, its sides should have equal
length. Measure of each of its angle is 108°.
A regular hexagon has all its sides equal and each of its angles
measures 120°.

6. LINES OF SYMMETRY
Triangle Square Pentagon Hexagon
3 lines of 4 lines of 5 lines of 6 lines of
Symmetry Symmetry Symmetry Symmetry

7. Points to remember
 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.

8. ROTATIONAL SYMMETRY
When an object rotates, its shapes and size do not change. The
rotation turns an object about a fixed point. This fixed
point is the centre of the rotation.
The angle of turning during rotation is called angle of
rotation. A full turn is 360o.

9. • Half turn means rotation by 180 °.
A quarter turn is rotation by 90 °.

10. WHICH LETTERS HAVROTATIONAL
SYMMETRY?
Next slide for answer

12. WHICH ROAD SIGNS HAVE GOT
ROTAIONAL SYMMETRY?
• Next slide for answer…

13. Oh! I lost Order 2 Order3
count…
Order2

14. Made by-
Samyak Jain