Ch 7'1 Ratio and Proportion

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Ch 7.1 Ratio and Proportion

• Use ratios and proportions

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• A ratio is a comparison of a number a and a
  nonzero number b using division.
• The ratio of a to b can be written three ways as
  a fraction a/b (or an equivalent decimal), as
  ab, or as a to b.
• A ratio is usually written in simplest form.
• Before you simplify a ratio, make sure that the
  units of the numerator and the denominator are
  the same.

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Use Ratios

• In the diagram, ABBC is 41 and AC 30.
• Find AB and BC.

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Use Ratios

• The perimeter of a rectangle is 80 feet. The
  ratio of the length to the width is 73.
• Find the length and the width of the rectangle.

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Solving Proportions

• An equation that states that two ratios are equal
  is called a proportion.
• The numbers b and c are the means of the
  proportion.
• The numbers a and d are the extremes of the
  proportion.

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• Cross Product Property
• Words In a proportion, the product of the
  extremes is equal to the product of the means.
• Symbols If , then .

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Solve a Proportion

• Solve the proportion

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Classwork

• Geometry book
• Page 361
• 1-12
• Neighbor help is ok