1. CORRECT HOMEWORK
TAKE OUT YOUR WORKBOOK

2. Workbook p.216 a) k b) 1. 1.5 or 0.67 2. x=6 a) x=1.6 y=1.8
b) x=4 y= z=5.4

3. Workbook p # 3 F B 5 6 3 A C E 4 D
So…
3. a) 1.2 b)
2. 4.8
Step 1 – Find the missing side 5
Step 2 – Find k
k = 6 = 1.2
Step 3 – Find the missing sides in the image
DF = 3x1.2 = 4.8
DE = 4x1.2 = 3.6

4. Workbook p.216 4. Missing side in this triangle is 6 (Pythagoras)
New triangle:
5. a) True
b) False
c) True
d) False
e) True 12
*** multiply the initial’s
side lengths by 3 2 9 15

5. Workbook p. 217 Activity 3 1.5 Yes
*** The point of this is to show you that the ratio of perimeters is just k!

6. Workbook p. 221 IMPORTANT QUESTION a) (Find k first, which was 1.5)
Hint hint…
a) (Find k first, which was 1.5)
x = y = 4.5
b) (Find k first, which was 7/5 = 1.4)
x = 21
Cone’s new dimensions:
radius: 9 height: 12
This makes a right-angle triangle, to find slant height use Pythagoras!
New slant height: 15cm 12 9

7. Workbook p. 221
a) False
b) True
c) True
d) True
e) False

8. Ratio of Areas

9. How to Find the Area of Similar Solids
Scale Factor: k2
area of the initial ˣ k2 = area of the image

10. Example 1 Step 1 – Find k k = 6 = 2 3 Step 2 – Find the area
of the initial
3x5=15cm2
Step 3 – Find the area
of the image
15 x 22 = 60cm2
3cm
5cm
6cm

11. How to find k given the areas?
Area = 64cm2
Area= 16cm2
Step 1 – Calculate the ratio of their areas
k2 = area of image = 64 = 4
area of initial
Step 2 – Convert to find k
k2 = 4
k = √4
k = **remember k is also the
ratio of the perimeters

12. Example 2 Step 1 – Find k k = 12 = 2 6
4cm
6cm
12cm
Step 1 – Find k
k = 12 = 2 6
Step 2 – Find the area of the initial
4 x 6=24cm2
Step 3 – Find the area of the image
24 x 22 = 96cm2

13. Workbook p. 217 Activity 4 p. 218 (all) p. 221 Activity 3
Homework – Start Now
Workbook
p. 217 Activity 4
p. 218 (all)
p. 221 Activity 3