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# Scale drawing ppt

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• 1. 7-7 Scale Drawings 7-7 Scale Drawings Warm Up Problem of the Day Lesson PresentationPre-Algebra Pre-Algebra
• 2. 7-7 Scale Drawings Warm Up Evaluate the following for x = 16. 1. 3x 48 2. 3 x 12 4 Evaluate the following for x = 2. 5 1 3. 10x 4 4. 1x 4 10Pre-Algebra
• 3. 7-7 Scale Drawings Problem of the Day An isosceles triangle with a base length of 6 cm and side lengths of 5 cm is dilated by a scale factor of 3. What is the area of the image? 108 cm2Pre-Algebra
• 4. 7-7 Scale Drawings Learn to make comparisons between and find dimensions of scale drawings and actual objects.Pre-Algebra
• 5. 7-7 Scale Drawings Vocabulary scale drawing scale reduction enlargementPre-Algebra
• 6. 7-7 Scale Drawings A scale drawing is a two-dimensional drawing that accurately represents an object. The scale drawing is mathematically similar to the object. A scale gives the ratio of the dimensions in the drawing to the dimensions of the object. All dimensions are reduced or enlarged using the same scale. Scales can use the same units or different units.Pre-Algebra
• 7. 7-7 Scale Drawings Scale Interpretation 1:20 1 unit on the drawing is 20 units. 1 cm: 1 m 1 cm on the drawing is 1 m. 1 1 4 in. = 1 ft 4 in. on the drawing is 1 ft. Reading Math The scale a:b is read “a to b.” For example, the scale 1 cm:3 ft is read “one centimeter to three feet.”Pre-Algebra
• 8. 7-7 Scale Drawings Additional Example 1A: Using Proportions to Find Unknown Scales or Lengths A. The length of an object on a scale drawing is 2 cm, and its actual length is 8 m. The scale is 1 cm: __ m. What is the scale? 1 cm = 2 cm Set up proportion using scale length . xm 8m actual length 1  8 = x  2 Find the cross products. 8 = 2x 4=x Solve the proportion. The scale is 1 cm:4 m.Pre-Algebra
• 9. 7-7 Scale Drawings Additional Example 1B: Using Proportions to Find Unknown Scales or Lengths B. The length of an object on a scale drawing is 1.5 inches. The scale is 1 in:6 ft. What is the actual length of the object? 1 in. = 1.5 in. Set up proportion using scale length . 6 ft x ft actual length 1  x = 6  1.5 Find the cross products. x=9 Solve the proportion. The actual length is 9 ft.Pre-Algebra
• 10. 7-7 Scale Drawings Try This: Example 1A A. The length of an object on a scale drawing is 4 cm, and its actual length is 12 m. The scale is 1 cm: __ m. What is the scale? 1 cm = 4 cm Set up proportion using scale length . xm 12 m actual length 1  12 = x  4 Find the cross products. 12 = 4x 3=x Solve the proportion. The scale is 1 cm:3 m.Pre-Algebra
• 11. 7-7 Scale Drawings Try This: Example 1B B. The length of an object on a scale drawing is 2 inches. The scale is 1 in:4 ft. What is the actual length of the object? 1 in. = 2 in. Set up proportion using scale length . 4 ft x ft actual length 1  x = 4 2 Find the cross products. x=8 Solve the proportion. The actual length is 8 ft.Pre-Algebra
• 12. 7-7 Scale Drawings A scale drawing that is smaller than the actual object is called a reduction. A scale drawing can also be larger than the object. In this case, the drawing is referred to as an enlargement.Pre-Algebra
• 13. 7-7 Scale Drawings Additional Example 2: Life Sciences Application Under a 1000:1 microscope view, an amoeba appears to have a length of 8 mm. What is its actual length? 1000 = 8 mm scale length 1 x mm actual length 1000  x=1  8 Find the cross products. x = 0.008 Solve the proportion. The actual length of the amoeba is 0.008 mm.Pre-Algebra
• 14. 7-7 Scale Drawings Try This: Example 2 Under a 10,000:1 microscope view, a fiber appears to have length of 1mm. What is its actual length? 10,000 = 1 mm scale length 1 x mm actual length10,000  x=1  1 Find the cross products. x = 0.0001 Solve the proportion. The actual length of the fiber is 0.0001 mm.Pre-Algebra
• 15. 7-7 Scale Drawings 1 A drawing that uses the scale 4 in. = 1 ft 1 is said to be in 4 in. scale. Similarly, a 1 drawing that uses the scale 2 in. = 1 ft is 1 in 2 in. scale.Pre-Algebra
• 16. 7-7 Scale Drawings Additional Example 3A: Using Scales and Scale Drawings to Find Heights A. If a wall in a 1 in. scale drawing is 4 in. tall, 4 how tall is the actual wall? 0.25 in. = 4 in. scale length Length ratios are 1 ft x ft. actual length equal.0.25  x=1  4 Find the cross products. x = 16 Solve the proportion. The wall is 16 ft tall.Pre-Algebra
• 17. 7-7 Scale Drawings Additional Example 3B: Using Scales and Scale Drawings to Find Heights B. How tall is the wall if a 1 in. scale is used? 2 0.5 in. = 4 in. scale length Length ratios are 1 ft x ft. actual length equal. 0.5  x=1  4 Find the cross products. x=8 Solve the proportion. The wall is 8 ft tall.Pre-Algebra
• 18. 7-7 Scale Drawings Try This: Example 3A A. If a wall in a 1 in. scale drawing is 0.5 in. 4 thick, how thick is the actual wall?0.25 in. = 0.5 in. scale length Length ratios are 1 ft x ft. actual length equal. 0.25  x=1  0.5 Find the cross products. x=2 Solve the proportion. The wall is 2 ft thick.Pre-Algebra
• 19. 7-7 Scale Drawings Try This: Example 3A Continued B. How thick is the wall if a 1 in. scale is used? 2 0.5 in. = 0.5 in. scale length Length ratios are 1 ft x ft. actual length equal. 0.5  x=1  0.5 Find the cross products. x=1 Solve the proportion. The wall is 1 ft thick.Pre-Algebra
• 20. 7-7 Scale Drawings Lesson Quiz 1. What is the scale of a drawing in which a 9 ft wall is 6 cm long? 1 cm = 1.5 ft 2. Using a 1in. = 1 ft scale, how long would a 4 drawing of a 22 ft car be? 5.5 in. 3. The height of a person on a scale drawing is 4.5 in. The scale is 1:16. What is the actual height of the person? 72 in. The scale of a map is 1 in. = 21 mi. Find each length on the map. 4. 147 mi 7 in. 5. 5.25 mi 0.25 in.Pre-Algebra