1. Homework Correction Take out your workbook!

2. Workbook p.217
Activity 4 2 4
4=22

3. Workbook p.218 #6 Ratio of heights: 1.5 Ratio of perimeters: 1.5
Ratio of Areas: 2.25
Ratio of heights: 1.67
Ratio of perimeters: 1.67
Ratio of Areas: 2.78

4. Workbook p.218 #7 #8 k= 3 0.8 Perimeter of initial: 10cm
# #8 k=
Perimeter of initial: 10cm
Perimeter of image: 30cm #9
Area of initial: 5.1cm2 k2=2.25 so k=1.5
Area of image: 45.9cm2 Per. of small:20cm
Per. of large:30cm
#10
Big area: 600  cost per m2: 12$
Small rectangle’s dimensions: 15 by 10
small area: 150
Cost of small: 150x12=1800

5. Ratio of Volumes

6. How to find the Volume of the image
Scale Factor: k3
Volume of the initial x k3 = volume of the image

7. Example 1 Find the volume of the image. Step 1 – Find k k = 6 = 2 3
V=???cm3
Initial
V=60cm3 3 4 6 5
Step 1 – Find k
k = 6 = 2 3
Step 2 – Find the volume of the initial
v=5x4x3 = 60cm3
Step 3 – Find the volume of the image
60x23 = 480cm3

8. Example 2 Find the radius of the image. Step 1 – Find k3V= V=
Step 1 – Find k3
k3 = = 3.24
Step 2 – Find k
k=³√ =
Step 3 – Find the radius of the image
12.5 x = 18.47

9. Things to Remember about Similarity
k is the ratio of sides(and perimeter)
k2 is the ratio of area
k3 is the ratio of volume

10. To get from one ratio to another
Ratio of volume to ratio of sides  k3 to k
³√ k3 = k
Ratio of volume to ratio of areas  k3 to k2
³√ k3 = k then square it to get k2
Ratio of areas to ratio of volumes  k2 to k3
√ k2 = k then cube it to get k3

11. Homework - START NOW 
Workbook
p # 5 to 9
p all