Use Proportions to Solve Geometric Problems
6.2
Proportion Properties
• The Reciprocal Property:– If two ratios are equal, then their
reciprocal is also equal.
– Basically, you can flip ratios to make new equivalent ratios.
Examples
If , then 147
6 x
x
14
6
7
Proportion Properties
• If you have 2 ratios equal to each other, then the numerators can be turned into a new ratio and the denominators into another new ratio.
Examples
Proportion Properties cont.
• You can add the denominator of each ratio to the numerator to get a new ratio.
Examples
True or False?true
true
false
true
True or False?false
true
true
true
True or False?false
true
true
BA = 12, BD = x – 3 = 12 – 3 = 9
What do I know?
XW = 1, XY = 3, YZ = 2, and WV is unknown so WV = x
2
3
x
1 1(2) = 3x 2 = 3x
x3
2
SR = 3, RQ = 4, ST = 6, and TU = x
x
6
4
3
)4(63 x 243 x 8x
BC = x, AB = 12, CD = 24, and DE = 18
18
24
12
x )24(1218 x 28818 x16x
HI = 21, GH = 14, JK = x, and KD = 12
1214
21 x )12(2114 x 25214 x 18x
301218 KDJKJD
Worksheet
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