CORRECT HOMEWORK TAKE OUT YOUR WORKBOOK

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=4.5 z=5.4

Workbook p. 216 # 3 F B 5 6 3 A C E 4 D So… 3. a) 1.2 b) 1. 3.6 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

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

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

Workbook p. 221 IMPORTANT QUESTION a) (Find k first, which was 1.5) Hint hint… a) (Find k first, which was 1.5) x = 6 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

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

Ratio of Areas

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

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

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 16 Step 2 – Convert to find k k2 = 4 k = √4 k = 2 **remember k is also the ratio of the perimeters

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

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