6.2.1 Use Proportions to solve Geometry Problems.
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6.2.1 Use Proportions to solve Geometry Problems
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Transcript of 6.2.1 Use Proportions to solve Geometry Problems.
6.2.1 Use Proportions to solve Geometry Problems
For any proportion, the reciprocal is also true D
C
B
A C
D
A
B
• Write and equivalent proportion:
x
x
5
1
10
2
5
1
10
2
1
5
2
10
1
5
2
10 x
x
• Cross multiply to check your work:
1*105*2
5*21*10
10*1)5(2 xx
)5(21*10 xx
For any proportion the means can be interchanged to make an equivalent proportion
D
C
B
A
D
B
C
A
• Write an equivalent proportion using the mean interchange property
5
1
10
2 x
x
5
1
10
2
• Cross multiply to check your work:
For any proportion the denominators can be added to the numerators to make an equivalent proportion
D
C
B
A
D
DC
B
BA
• Write an equivalent proportion using the Proportional Addition Property
5
1
10
2
x
x
5
1
10
2
• Cross multiply to check your work:
A scale is when something is drawn based on a ratio
Example: in real life my car is 17 ½ feet long, what is the scale based on the model? (show model car to class)
p. 367 3, 5, 8, 11, 16, 19, 21, 24, 37
