11.3 – Perimeter and Area of Similar Figures

Find the ratio of the sides, perimeters, and areas of the similar rectangles.

9

36

2

Ratio of Sides: 32

P = 9 + 3 + 9 + 3

P = 24u

P = 6 + 2 + 6 + 2

P = 16u

Ratio of Perimeters:2416

= 32

Find the ratio of the sides, perimeters, and areas of the similar rectangles.

9

36

2

A = bhA = (9)(3)A = 27u2

A = bhA = (6)(2)A = 12u2

Find the ratio of the sides, perimeters, and areas of the similar rectangles.

9

36

2

Ratio of Areas:2712

= 94

If two polygons are _____________ with the lengths of corresponding sides in the ratio ___________, then the ratio of their areas is ____________.

similara:b

a2:b2

S P A

ab

ab

a2

b2

The ratio of the areas of two similar figures is given. Write the ratio of the lengths of corresponding sides.

Ratio of areas = 4:225

S P A

4 .

225 2 .

15 2 .

15

The ratio of the areas of two similar figures is given. Write the ratio of the lengths of corresponding sides.

Ratio of areas = 16:49

S P A

16.

4947

47

The ratio of the areas of two similar figures is given. Write the ratio of the lengths of corresponding sides.

Ratio of areas = 36:4

S P A

36.

462

62

Use the given area to find XY.

S P A

144 36

12 6

=21

21

2 10

1 x=

2x =10

x = 5in

Use the given area to find XY.

S P A

168378

23

=49

23

2 8

3 x=

2x =24

x = 12cm

Corresponding lengths in similar figures are given. Find the ratios (shaded to unshaded) of the perimeters and areas. Find the unknown area.

S P A

28

1 .

1614

= 14

1 3

16 x=

x = 48ft2

Corresponding lengths in similar figures are given. Find the ratios (shaded to unshaded) of the perimeters and areas. Find the unknown area.

S P A

915

9 .

2535

= 35

9

25 225

x=

25x = 2025

x = 81in2

11.3 740-742 5-15 odd, 26-28, 35

HW Problems

#28

S P A

23

4.

96090

= 23

4

9 20

x=

9x = 80

x = 8.88 B