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4.5 Similar FiguresI can use proportions to find missing
lengths in similar figures.
Same shape, but not necessarily same size
You can use proportions to find missing side lengths of similar figures.
The symbol ∼ means “is similar to”
Similar Figures
∆ABC ∼ ∆FGH
This means the triangles are similar.
In similar figures, corresponding angles are equal, and corresponding side lengths are proportional.◦ The order of the letters when making similar
figures is important
Example
If ∆ABC ∼ ∆DEF, what is the length of side DE?
Set up a proportion
Cross product 10(12) = 16(DE) 7.5 = DE
Practice
Using the same figure, find AC
You Try!
Use proportions to find measurement that you cannot find by measuring directly.
Create a proportion
x=25 feet
Indirect Measurement
ODDS ONLY P.153 #7-19
Assignment
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