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4.2 Scale Diagrams

4.2 Scale Diagrams. Learning Outcome: To be able to identify and interpret the scale factor using the scale diagram and determine if something is proportional to its original. Scale.

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4.2 Scale Diagrams

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  1. 4.2 Scale Diagrams Learning Outcome: To be able to identify and interpret the scale factor using the scale diagram and determine if something is proportional to its original

  2. Scale • A comparison between the actual size of an object and the size of its diagram/image; can be expressed as a ratio, fraction, percent, in words, or in a diagram. • Ratio 1:2 • Fraction ½ • Percent 50%

  3. Scale Diagram • A drawing that is similar to the actual figure or object. May be smaller or larger than the actual object, but must be in the same proportions.

  4. Proportion • is a relationship that shows two ratios/rates are equal. It can be written in fraction or ratio form. Example: The ratio 1 girl to 4 students is the same as 5 girls to 20 students. As a proportion write or 1:4 = 5:20

  5. Example 1: Use the scale factor to determine the actual length of the object skateboard? The scale diagram of a skateboard uses a scale of 1:14. What is the actual length of the skateboard? Method 1: Use the Scale 5.5cm The scale 1:14 means that the actual dimensions of the skateboard are 14 times those of the diagram. Multiply the length of the skateboard in the diagram by 14. 5.5 x 14 = 77 The actual length of the skateboard is 77cm.

  6. Example 1: Use the scale factor to determine the actual length of the object skateboard? The scale diagram of a skateboard uses a scale of 1:14. What is the actual length of the skateboard? Method 2: Use a Proportion 5.5cm Set up a proportion using the scale and the measurement that is given. Scale = Note: The scale 1:14. The diagram measures 5.5 cm. The actual measurement is unknown.

  7. Show you Know The scale for the diagram of the chinook salmon is 1:9.2 Calculate the actual length of the salmon. Scale: 9.2 x 5 = 46cm

  8. Example 2: Determine the Scale Factor An actual Canadian quarter has a diameter of 23.88mm. Calculate the scale factor used to create the diagram of the quarter. Express your answer to the nearest tenth. First: Measure the diameter of the diagram of the quarter. It measures 1.4cm Second: Set up a proportion using the scale and the measurement that is given. Note: The diagram is a reduction! The scale factor will be less than 1. Scale =

  9. Assignment • Page 142 (4-11, 14,18) 5cm

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