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Section 7-1

Using Proportions. Section 7-1. Ratio. A ratio is a comparison of two numbers such as a : b. Ratio:. When writing a ratio, always express it in simplest form. ** Ratios must be compared using the same units. A ration can be expressed: 1. As a fraction

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Section 7-1

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  1. Using Proportions Section 7-1

  2. Ratio A ratio is a comparison of two numbers such as a : b. Ratio: When writing a ratio, always express it in simplest form. ** Ratios must be compared using the same units. A ration can be expressed: 1. As a fraction 2. As a ration 3 : 7 3. Using the word “to” 3 to 7

  3. A 8 10 D 4.8 3.6 B C 6 Example: What is the ration of side AB to side CB in the triangle? Now try to reduce the fraction.

  4. A 8 10 D 4.8 3.6 B C 6 Example: What is the ration of side DB to side CD in the triangle? Now try to reduce the fraction.

  5. Ratio: Decimal: Example………. A baseball player goes to bat 348 times and gets 107 hits. What is the players batting average? Solution: Set up a ratio that compares the number of hits to the number of times he goes to bat. Convert this fraction to a decimal rounded to three decimal places. The baseball player’s batting average is 0.307 which means he is getting approximately one hit every three times at bat.

  6. Proportion Proportion: An equation that states that two ratios are equal. Terms First Term Third Term Second Term Fourth Term To solve a proportion, cross multiply the proportion: ad=bc

  7. = 12 • 3 4• x Proportions- examples…. Example 1: Solve the proportion. 4x = 36 x = 9 4x= 36 4 4

  8. x 2 ft 84 yards 356 yards Example 2: Find the value of x. Multiply by 3 to change yards into feet.

  9. Examples: Find the measure of each angle. • Two complementary angles have measures in the ration 2 : 3. • Two supplementary angles have measures in the ratio 3 : 7. • The measures of the angles of a triangle are in a ratio of 2 : 2 : 5. • The perimeter of a triangle is 48cm and the lengths of the sides are in a ratio of 3 : 4 : 5. Find the length of each side. 36 and 54 54 and 126 40, 40, and 100 12cm, 16cm, and 20cm

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