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Section 6.3 Solving Proportions Using Cross Product A cross product of two ratios is the product of the numerator of one ratio and the denominator of the other ratio.
You can use cross products to tell whether two ratios form a proportion. If the cross products are equal, then the ratios form a proportion.
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Example 1
Tell whether the ratios form a proportion.
a.) b.)
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Checkpoint Tell whether the ratios form a proportion Mar 18­11:57 AM
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Cross Products Property
The cross products of a proportion are equal.
Given that , you know that You can use the cross products property to solve proportions.
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Example 2
Human hair grows about 0.7 centimeters in 2 weeks. How long does hair take to grow 14 centimeters?
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Checkpoint Use cross products property to solve the proportion Mar 18­12:00 PM
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Summary: Methods for Solving a Proportion
To solve the proportion ,
1. Equivalent Ratios
2. Algebra
3. Cross Products
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