© Boardworks Ltd 2001 Menu © Boardworks Ltd 2001 Enlargements 1.

© Boardworks Ltd 2001

Menu


Enlargements 1


Menu


ENLARGEMENTS

B. DRAWING ENLARGEMENTS

A. SCALE FACTORS

C. CENTRES OF ENLARGEMENT

D. OTHER SCALE FACTORS


Menu


Enlargements

Odd One Out A1 A2 A3 A4 A5 A6

Guess the scale factor B1 B2 B3

Practice exercises exploring the idea of scale factor. Some of the numbers involved are deliberately tricky in order to generate discussion and “hands on” measurement of corresponding lengths.

DRAWING ENLARGMENTS: This section demonstrates how enlargements are drawn from a given center of enlargement and a scale factor.

General Examples C1 C2 C3

C4 C5 Examples on Grids

A number of practice exercises where the idea of “scale factor“ is explored.

F1 F2 F3

E1 E2 E3 Fractional Enlargements

Negative Enlargements

FINDING THE CENTRE OF ENLARGEMENT: How lines are drawn back through corresponding points to give the centre of enlargement.

D1 D2 D3 D4 D5 Example 5 Spelt out!


Menu


SECTION A

A. BASICS + SCALE FACTORS

x 2 ?


Menu


Odd One Out?

In each of the diagrams TWO have

been enlarged by the SAME scale factor.

Look carefully at the lengths on the

diagrams and ....

Spot the ODD ONE OUT?


Menu


A

B

C

Odd One Out?A1


Menu


A x 2

B

C x 2

x 3

Odd One Out?A1


Menu


A

B

C

Odd One Out?A2


Menu


A x 2

B

C

x 2

x 3

Odd One Out?A2


Menu


A

B

C

Odd One Out?A3


Menu


A x 1.5

B

C x 1.5

x 2

Odd One Out?A3


Menu


A

B

C

Odd One Out?A4


Menu


A x 3

B

C

x 3

x 2

Odd One Out?A4


Menu


A

B

C

Odd One Out?A5


Menu


A

B

C

x 1.5

x 2

x 2

Odd One Out?A5


Menu


A

B

C

Odd One Out?A6


Menu


A x 2

B

C x 2

x 3

Odd One Out?A6


Menu


Guess the Scale Factor?

A B C Dx 2 x 4x 3 x 5

B1


Menu



x 3B C Dx 2 x 4 x 5

A

B1


Menu



B C Dx 2 x 4x 3 x 5

A

B2


Menu


x 2A C Dx 3 x 4 x 5

B

Guess the Scale Factor?B2


Menu



Need to be accurate here!!!

B C Dx 1.25 x 2x 1.5 x 2.25A

B3


Menu



Need to be accurate here!!!

BCx 1.25 x 2x 1.5A x 2.25DB

B3


Menu


SECTION 2

Drawing enlargements


Menu


Drawing Enlargements

• Start with a point and a shape

• Draw lines to each point on the shape

Scale Factor + 2Multiply the length of each line by 2

Can you see the outline of the IMAGE?

C1


Menu





Scale Factor + 3

Multiply the length of each line by 3

Can you see the outline of the IMAGE?

C2


Menu





Scale Factor + 2

Multiply the

lengths by 2Note the outline

of the IMAGE

C3


Menu


0

1

2

3

4

5

6

7

8

9

10

0 1 2 3 4 5 6 7 8 9 10

Enlarge this shape by ...

Scale factor + 2

Centre of Enlargement

( 1 , 2 )

• Multiply the length of each line by 2

• Can you see the outline of the image?

Drawing EnlargementsC4


Menu


0

1

2

3

4

5

6

7

8

9

10

0 1 2 3 4 5 6 7 8 9 10

Enlarge this shape by ...

Scale factor + 2

Centre of Enlargement

( 9 , 10 )

• Multiply the length of each line by 2

• Can you see the outline of the image?

Drawing EnlargementsC5


Menu


Finding Centres of Enlargement

xCentre


Menu


0

1

2

3

4

5

6

7

8

9

10

0 1 2 3 4 5 6 7 8 9 10

The Shape

The Image

Now draw the lines back to the ...CENTRE OF ENLARGEMENT

x

Find the Centre of Enlargement?

( 1 , 2 ) SCALE FACTOR + 2

D1


Menu


0

1

2

3

4

5

6

7

8

9

10

0 1 2 3 4 5 6 7 8 9 10

The Shape

The Image


x



D2


Menu


0

1

2

3

4

5

6

7

8

9

10

0 1 2 3 4 5 6 7 8 9 10

The Shape

The Image


x



D3


Menu


0

1

2

3

4

5

6

7

8

9

10

0 1 2 3 4 5 6 7 8 9 10

The Shape

The Image


x



D4


Menu


0

1

2

3

4

5

6

7

8

9

10

0 1 2 3 4 5 6 7 8 9 10

The Shape

The Image


x


( 7 , 1 ) SCALE FACTOR + 0.5

D5


Menu


0

1

2

3

4

5

6

7

8

9

10

0 1 2 3 4 5 6 7 8 9 10

WATCH THE

ORDER CAREFULLY

The Shape

The Image

x

Why + 0.5 and not + 2 ???

( 7 , 1 ) SCALE FACTOR + 0.5

D5


Menu


Fractional and Negative Enlargements

x 0.5

E


Menu


Fractional Enlargement 1

x divide all lengths by 3 13

E1


Menu



x multiply all lengths by 0.75 34

E2


Menu



x multiply all lengths by 0.6 35

E3


Menu


Negative Enlargement 1

x -1 multiply all lengths by 1 and draw in the opposite (negative) direction.

E4


Menu




E5


Menu




E6

© Boardworks Ltd 2001 Menu © Boardworks Ltd 2001 Enlargements 1.

Documents

Transcript of © Boardworks Ltd 2001 Menu © Boardworks Ltd 2001 Enlargements 1.