8.1 Similar Polygons

What is a ratio? An expression that compares two quantities by division Can be written in 3 ways

Find and simplify the following ratios Ratio of girls to boys in the classroom. Ratio of boys to girls in the classroom. Ratio of filled desks to empty desks. Ratio of people with chrome books on their desk to people with out them on their desk. Student to teacher ratio. Ratio of eyes to legs currently in the room. Ratio of fingers to ears currently in the room.

Proportion An equation that sets two ratios equal to each other.

Challenge If ratio X and ratio Y form a proportion, and ratio Y and ratio Z form a proportion, then do ratio X and ratio Z form a proportion?

Complete the table PolygonFind the perimeter Find the areaPrismVolume Square ABCD with side length 2: Cube with side length 2: Square A’B’C’D with side length 4 (Scale Factor= 2): Cube with side length 4: Triangle EFG with b = 3, h =4: Triangular Prism with base area = 12, height = 5. Triangle E’F’G’ with b = 9, h = 12: (Scale Factor=3) Triangular Prism with base area = 108, height = 15

PolygonFind the perimeter Find the area PrismVolume Square ABCD with side length 2: =8 (2)(2) =4 Cube with side length 2:(2)(2)(2) =8 Square A’B’C’D with side length 4 (Scale Factor= 2): =2( ) =16 (4)(4) (2(2))(2(2)) 4(2)(2) =16 Cube with side length 4:(4)(4)(4) 2(2)2(2)2(2) 8(2)(2)(2) =64 Triangle EFG with b=3, h=4, s=5: = 12 (3)(4)/2 =6 Triangular Prism with base area = 12, height = 5. (12)(5) =60 Triangle E’F’G’ b=9, h=12, s=15 : (Scale Factor=3) ( ) =36 (9)(12)/2 3(3)3(4)/2 9(3)(4)/2 Triangular Prism with base area = 108, height = (15) 9(12)3(5) 27(12)(5)

-Corresponding Angles are Congruent -Corresponding Sides and Special Segments are Proportional Definition of Similar Polygons

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