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Symmetry and Transformation

- Form 1 Mathematics
- Chapter 9

Reminder

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

Symmetry

- Reflectional Symmetry (????)
- Rotational Symmetry (????)

Reflectional Symmetry (p.78)

1 axis of symmetry

Reflectional Symmetry

4 axes of symmetry

Reflectional Symmetry

4 axes of symmetry

Reflectional Symmetry

6 axes of symmetry

Reflectional Symmetry

Rotational Symmetry (p.80)

2-fold rotational symmetry

Rotational Symmetry

Centre Of Rotation

3-fold rotational symmetry

Rotational Symmetry

Centre Of Rotation

3-fold rotational symmetry

5-fold rotational symmetry

Rotational Symmetry

Rotational Symmetry

Centre Of Rotation

5-fold rotational symmetry

Rotational Symmetry

Time for Practice

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

Transformation (p.86)

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

Lets look at this now

Translation (??, p.94)

It

translates

the figure

to the left

by 1 unit.

Translation (??)

A

A

B

C

C

B

B

A

Arrow A is translated 4 units to the right and 2

units downwards to give Arrow C.

C

C

Transformation

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

Lets look at this now

(No Transcript)

Reflection (??, p.87)

A

B

It

reflects

the figure

about the line of reflection

AB.

Reflection (??)

X

G

G

E

F

F

E

A

A

D

C

D

C

B

B

Y

(No Transcript)

Figure A

Figure B

Line of reflection

Whats this line called?

Transformation

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

Lets look at this now

Centre of rotation

G

anti-clockwise

by 90o.

It

rotates

the figure

around point G

What is point G called?

Rotation (??, p.91)

X

G

G

E

F

F

E

A

A

D

C

D

C

B

B

Y

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

(No Transcript)

Transformation

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

Lets look at this now

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

Enlargement (??, p.96)

The robot enlarges the figure by 2 times

This is called ENLARGEMENT.

Enlargement (??)

A

B

A

B

C

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

Reduction (??, p.96)

The robot reduces the figure by one half

This is called REDUCTION.

Reduction (??)

A

B

A

B

C

What do we call this?

What do we call this?

?O

Time for Practice

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

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

- Enjoy the world of Mathematics!