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# Hot Topics page 411 - PowerPoint PPT Presentation

Hot Topics page 411. Numbers 1-10. Give the scale factor. 25 20. 20 16. 4 5 . 25/20 = 5/4 or 20/16 = 5/4. Give the scale factor. 14 14 14. 10 10 10. 7 5. 10/14 = 5/7.

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### Hot Topics page 411

Numbers 1-10

25

20

20

16

4 5

25/20 = 5/4 or 20/16 = 5/4

14

14

14

10

10

10

7 5

10/14 = 5/7

A document measuring 28 cm by 20 cm is enlarged by a scale factor of 3/2. What are the new dimensions?

28 cm x

20 cm y

2 3

3/2 = x/28 so x = 42

3/2 = y/20 so y = 30

A photograph 8 in. by 6 in. is reduced to a length of 6 in. What is the width?

8 in 6 in

6 in x

8/6 = 6/x so x = 4.5 in.

The scale factor is ½. What are the new dimensions? What is the width?

26 m

10m

24m

2 1

5m, 13m, 12m

The scale on a map is 1 in. = 10 mi. On the map, 2 towns are 3.5 in. apart. How far apart are they actually?

1 in/10 mi = 3.5 in/x

so, x = 35 mi

The scale on a map is 1 cm = 5 km. What length on the map would a road be that is 12.5 km long?

1 cm/5 km = x / 12.5 km

so, x = 2.5 cm

The scale factor of 2 similar figures is 4. If the smaller rectangle has an area of 2 sqft, what is the area of the larger figure?

1 4

Area = 2 sqft

4 x 4 = 16 x 2 = 32 sqft

A square park has sides of 12 km. What is its area on a map that has a scale of 1 cm = 10 km?

1 cm/10 km = x / 12 km

So, x = 1.2 cm

1.2 x 1.2 = 1.44 sq cm

The scale factor of the 2 similar pentagons is 2/3. Find the new dimensions.

• 15 15

• 12 12

• 21

• 10

8

14

3 2