Scale Factor

and Dilation Part 2

Draw a rectangle on your graph paper with dimensions of 6cm by 4cm

6cm

4cm

Length width perimeter area

24cm²20cm4cm6cm

Draw another rectangle on your graph paper where the above dimensions have been multiplied by a scale factor of 2

12cm

8cm

96cm²40cm8cm12cm

Draw a rectangle on your graph paper with dimensions of 6cm by 4cm

6cm4cm

Length width perimeter area

24cm²20cm4cm6cm

Draw another rectangle on your graph paper where the above dimensions have been multiplied by a scale factor of 3

18cm

12cm

216cm²60cm12cm18cm

The rectangle below will be dilated by a scale factor of 3. What is the new

rectangle’s area and perimeter?

10m

2m

P = 2 + 10 + 2 + 10P = 24 m

A = 2 • 10A = 20 m²

6 m

30m

P = 6 + 30 + 6 + 30P = 72 m

A = 6 • 30A = 180 m²

Sooo….. What really happened??

P = 24 m

A = 20 m²

P = 72 m

A = 180 m²

Old perimeter New perimeterScale factor

3

Old area New areaScale factor

3

24 • 3 = 72Multiply the old perimeter by the scale factor to get the new perimeter

Multiply the old area by the scale factor squared to get the new area

20 • 3 ≠ 180

20 • 3² = 18020 • 9 = 180

Which statement best describes the change in the perimeter of a rectangle if all of its side lengths

are multiplied by 4?A The new perimeter will be 12 times as large as the perimeter of the original rectangle

B The new perimeter will be 16 times as large as the perimeter of the original rectangle

C The new perimeter will be 4 times as large as the perimeter of the original rectangle

D The new perimeter will be 8 times as large as the perimeter of the original rectangle

Which statement best describes the change in the area of a

rectangle if all of its side lengths are multiplied by 4?

A The new area will be 12 times as large as the area of the original rectangle

B The new area will be 16 times as large as the area of the original rectangle

C The new area will be 4 times as large as the area of the original rectangle

D The new area will be 8 times as large as the area of the original rectangle

Answer bank for CBA review # 2

3.029

1112182060

68112.35113.04

310400

1536