Symmetry

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# Symmetry - PowerPoint PPT Presentation

Symmetry Two Types: 1. Line Symmetry (can be called reflectional symmetry )– if you can fold a shape and have the edges meet The place where you fold is called the line of symmetry More Line Symmetry reflectional symmetry Line Symmetry in the Alphabet

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## Symmetry

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Presentation Transcript
Symmetry

Two Types:

1. Line Symmetry (can be called reflectional symmetry)– if you can fold a shape and have the edges meet

• The place where you fold is called the line of symmetry
More Line Symmetry

reflectional symmetry

Line Symmetry in the Alphabet

Which letters have got lines of symmetry?

Click to see the lines of symmetry.

A

B

C

D

E

F

G

H

I

J

K

L

M

N

O

P

Q

R

S

T

U

V

W

X

Y

Z

Lines of Symmetry all around us

Which of these road signs have got lines of symmetry?

Click to see the lines of symmetry.

Examples:
• Do the following shapes have line symmetry? If so, how many lines of symmetry do they have?

a. b. c. d. e.

No Lines

1 Line

2 Lines

4 Lines

2 Lines

Rotational Symmetry

Optional – extra information

• 2. Rotational Symmetry: If you can turn the shape less than 360o and still have the same shape.
• Order of Rotational Symmetry: Is the number of rotations that must be made to return to the original orientation
• Minimum Rotational Symmetry: The smallest number of degrees a shape can be rotated and fit exactly on itself
• Hint: Take 360o divided by the number of sides/points.
Symmetry
• A figure that has rotational symmetry is its own image for some rotation of 180° or less. A figure that has point symmetry has 180° rotational symmetry.
• A square has 90° and 180° rotational symmetry with the center of rotation at the center of the square. A square also has point symmetry.
Identifying Rotational Symmetry
• Identify any rotational symmetry in the figure.
Identifying Rotational Symmetry
• This figure has rotational symmetry, It will coincide with itself after being rotated 90° or 180° in either direction.
Identifying Rotational Symmetry
• This figure has rotational symmetry. It will coincide with itself after being rotated 60°, 120°, or 180° in either direction.
Identifying Rotational Symmetry
• This figure has no rotational symmetry. It does have horizontal line of symmetry.
Rotational Symmetry all around us

Which road signs have got rotational symmetry?

Rotational Symmetry all around us

Which road signs have got rotational symmetry?

Rotational Symmetry all around us

Click to see the road signs with rotational symmetry.

Order 3

Order 2

Order 2

Rotational Symmetry all around us

Click to see more road signs with rotational symmetry.

Order 4

Order 3

Order 2

Rotational Symmetry all around us

Click to see more road signs with rotational symmetry.

Order 3

Order 2