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Do Now 10/12/09

Do Now 10/12/09. Copy HW in your planner. Text p. 165, #28-34 evens, #46-50 evens Text p. 171-172, #16-38 even In your journal, consider the following. On a bright sunny day, how can you determine the height of a tall object (i.e. flagpole) without physically measuring the object?. Objective.

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Do Now 10/12/09

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  1. Do Now 10/12/09 • Copy HW in your planner. • Text p. 165, #28-34 evens, #46-50 evens • Text p. 171-172, #16-38 even • In your journal, consider the following. On a bright sunny day, how can you determine the height of a tall object (i.e. flagpole) without physically measuring the object?

  2. Objective • SWBAT find ratios and write and solve proportions • SWBAT solve proportions using cross products

  3. RATIO- Section 3.5 “Write Ratios and Proportions” uses division to compare two quantities You can write ratios three different ways: a b a to b a:b

  4. 14 14 14 + 10 10 a. = = 14 7 7 24 12 5 home matches home matches b. = = = all matches away matches Try It Out… VOLLEYBALL A volleyball team plays 14 home matches and 10 away matches. a.Find the ratio of home matches to away matches. b.Find the ratio of home matches to all matches. SOLUTION

  5. PROPORTION- an equation that states that two ratios are equivalent.

  6. 330 . x 11 x x Solve the proportion = = 30 30 30 6 6 x = 11 11 6 6 30 30 = Try It Out… Write original proportion. Multiply each side by 30. Simplify. 55= x Divide.

  7. Section 3.6 “Solving Proportions Using Cross Products” If , then

  8. Solve the proportion = 8 6 8 6 x 15 15 x = 3 3 2 2 8 15 = x 6 = = x x x x – 6 – 6 3(x – 6) =2x Solve the proportion Write original proportion. Cross products property 120 = 6x Simplify. Write original proportion. 20=x Divide each side by 6. Cross products property 3x – 18 = 2x Distributive property 18 = x Subtract 3xfrom each side.

  9. 1 centimeters = 85 kilometers 1 d = 85 4.2 4.2 d SCALE - the SCALE of a drawing, map, or model relates the dimensions of the drawing, map, or model to the actual dimensions. Write and solve a proportion to find the distance dbetween Cleveland and Cincinnati if the distance on the map is about 4.2 centimeters. Cross products property d = 357 Simplify.

  10. The ship model kits sold at a hobby store have a scale of 1 ft : 600 ft. A completed model of the Queen Elizabeth II is 1.6 feet long. Estimate the actual length of the Queen Elizabeth II. 1 = 600 1.6 The actual length of the Queen Elizabeth II is about 960 feet. g SOLUTION Write and solve a proportion to find the length gof the Queen Elizabeth II. 1 · g = 600 · 1.6 Cross products property g = 960 Simplify.

  11. Indirect Measurements You measure the shadow of a telephone pole to be 24 ft. The shadow of a 5ft-tree is 4 ft. How tall is the telephone pole? H h S s

  12. Homework 24 • Text p. 165, #28-34 evens, #46-50 evens • Text p. 171-172, #16-38 even

  13. HomeworkReal-Life Applications Worksheet • 1) • 2) • 3) • 4) b. about 1 ¼ inches c. the city locations on the maps are approximations

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