Symmetry and Transformation

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Symmetry and Transformation

• Form 1 Mathematics
• Chapter 9

2
Reminder

• Lesson requirement
• Textbook 1B
• Workbook 1B
• Notebook
• Folder
• Before lessons start
• Desks in good order!
• No rubbish around!
• No toilets!

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Symmetry

• Reflectional Symmetry (????)
• Rotational Symmetry (????)

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Reflectional Symmetry (p.78)
1 axis of symmetry
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Reflectional Symmetry
4 axes of symmetry
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Reflectional Symmetry
4 axes of symmetry
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Reflectional Symmetry
6 axes of symmetry
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Reflectional Symmetry
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Rotational Symmetry (p.80)
2-fold rotational symmetry
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Rotational Symmetry
Centre Of Rotation
3-fold rotational symmetry
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Rotational Symmetry
Centre Of Rotation
3-fold rotational symmetry
5-fold rotational symmetry
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Rotational Symmetry
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Rotational Symmetry
Centre Of Rotation
5-fold rotational symmetry
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Rotational Symmetry
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Time for Practice

• Pages 84 85 of Textbook 1B
• Questions 2 10
• Pages 38 39 of Workbook 1B
• Questions 3 9

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Transformation (p.86)

• Four types of transformations
• Translation
• Reflection
• Rotation
• Enlargement / reduction

Lets look at this now
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Translation (??, p.94)
It
translates
the figure
to the left
by 1 unit.
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Translation (??)
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A
A
B
C
C
B
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B
A
Arrow A is translated 4 units to the right and 2
units downwards to give Arrow C.
C
C
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Transformation

• Four types of transformations
• Translation
• Reflection
• Rotation
• Enlargement / reduction

Lets look at this now
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(No Transcript)
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Reflection (??, p.87)
A
B
It
reflects
the figure
about the line of reflection
AB.
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Reflection (??)
X
G
G
E
F
F
E
A
A
D
C
D
C
B
B
Y
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(No Transcript)
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Figure A
Figure B
Line of reflection
Whats this line called?
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Transformation

• Four types of transformations
• Translation
• Reflection
• Rotation
• Enlargement / reduction

Lets look at this now
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Centre of rotation
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G
anti-clockwise
by 90o.
It
rotates
the figure
around point G
What is point G called?
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Rotation (??, p.91)
X
G
G
E
F
F
E
A
A
D
C
D
C
B
B
Y
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Rotation (??)
A
E
B
D
C
B
C
A
?O
D
E
The arrow ABCDE is rotated clockwise by 90 about
the point O to obtain image ABCDE
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(No Transcript)
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Transformation

• Four types of transformations
• Translation
• Reflection
• Rotation
• Enlargement / reduction

Lets look at this now
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The robot enlarges the figure to 2 units long and
2 units high
The robot ??? the figure to ?? units ???? and ??
units ????
Another way The robot ENLARGES the figure by 2
TIMES
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Enlargement (??, p.96)
The robot enlarges the figure by 2 times
This is called ENLARGEMENT.
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Enlargement (??)
A
B
A
B
C
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The robot reduces the figure to 1 unit long and 1
unit high
The robot ??? the figure to ?? units ???? and ??
units ????
Another way The robot REDUCES the figure by ONE
HALF
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Reduction (??, p.96)
The robot reduces the figure by one half
This is called REDUCTION.
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Reduction (??)
A
B
A
B
C
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What do we call this?
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What do we call this?
?O
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Time for Practice

• Pages 100 101 of Textbook 1B
• Questions 1 14
• Pages 40 41 of Workbook 1B
• Questions 1 2

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Reminder

• Missing Homework, Re-do Homework
• Today!
• SHW (I) and SHW (II)
• 11 Mar (Mon)
• External Review
• 13 Mar (Wed)
• Open Book Quiz
• 13 Mar (Wed)
• Close Book Quiz
• 15 Mar (Fri) To be confirmed

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• Enjoy the world of Mathematics!