1. 12-5 Areas and Volumes of Similar Solids

2. Rules Scale Factor – 2:3 – Also used for: dimensions (radius, length, slant height, base edge, etc.), perimeter/circumference Ratio of Areas –(2:3) 2 4:9 NEW!! Ratio of Volumes –(2:3) 3 8:27 Remember: If 2 Solids have the same scale factor, Then they are similar

3. EXAMPLE The circumferences of 2 similar cones are 8π and 6π. – What is the scale factor? – Ratio of diameters? – Ratio of heights? – Ratio of lateral areas? – Ratio of base areas? – Ratio of volumes? 4:3 16:9 64:27

4. For Same 2 Cones If you know the slant height of the first cone is 24, what is the slant height of the second cone? 4/3 = 24/x Cross Multiply: Watch the Whiteboard l=18 If the total area of the 2 nd cone is 36π, what is that total area of the 1 st cone? 16/9 = x/36π x = 64π *Watch me on the Whiteboard

5. TOO The ratio of Volumes for 2 solids is 125:64, Find: – A) Scale Factor – B) Ratio of Areas – C) Ratio of perimeters Answers: a) 5:4b) 25:16c) 5:4

6. Homework Page 511 #1-8, 11 Pg. 496 Self Test 1-6, skip 4 QUIZ Tomorrow!!