A13­5ProportionsAndSimilarFigs.notebook
September 25, 2015
Algebra 1
Ch.3 Notes Page 22
P22 3­5 Proportions and Similar Figures
Sep 2­8:31 AM
Review
To Solve Proportions...
Cross Multiply and Divide
x = 5
8 10
Sep 13­9:59 AM
1
A13­5ProportionsAndSimilarFigs.notebook
September 25, 2015
Similar Figures
Sep 13­9:59 AM
Find the Length of DE...
ABC ~ DEF
Sep 23­8:25 AM
2
A13­5ProportionsAndSimilarFigs.notebook
September 25, 2015
Indirect Measurement:
A tree casts a shadow 7.5ft long. A woman 5ft tall cast a shadow 3ft long. The triangle shown for the tree and its shadow is similar to the triangle shown for the woman and her shadow. How tall is the tree?
Sep 23­8:23 AM
Similar Figures
Scale Drawings are Similar Figures
(Maps/Blue Prints/Etc...)
Dilations are Similar Figures
(Make Pictures Bigger or Smaller)
Sep 23­8:30 AM
3
A13­5ProportionsAndSimilarFigs.notebook
September 25, 2015
Dilations
Scale Factor (How Big or Small)
Center of Dilation (Where to Start Counting)
Use the Origin
SF = 1/2
CoD = (0, 0)
Aug 29­8:24 AM
Example
SF = 2
CoD = (0, 0)
Aug 29­8:16 AM
4
A13­5ProportionsAndSimilarFigs.notebook
September 25, 2015
Maps
The scale on a map is 1in = 5mi.
The distance from Point A to Point B is 87mi.
How far would it be on the map?
Aug 29­8:36 AM
5