Scale Drawings

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Scale Drawings Scale Factor
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Ratio

• A ratio is a comparison of two quantities

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Scale

• A scale is a ratio between two sets of
  measurements.
• Examples
• Drawings ¼ inch 1 foot
• Maps 1 inch 250 miles

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Scale Drawing (Model)

• A scale drawing (model) is a drawing that uses a
  scale to make an object smaller than (reduction)
  or larger than (enlargement) the real object.

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Scale Factor

• A scale factor is a ratio used to enlarge or
  reduce similar figures.
• Examples enlarging a piece of candy for a
  drawingor the Willy Wonka Factory

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• The lengths and widths of objects of a scale
  drawing or model are proportional to the lengths
  and widths of the actual object.

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Practice Problems
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• A set of landscape plans shows a flower bed that
  is 6.5 inches wide. The scale on the plans is 1
  inch 4 feet.
• What is the width of the actual flower bed?
• What is the scale factor?

26 feet
1/48
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• The central chamber of the Lincoln memorial,
  which features a marble statue of Abraham
  Lincoln, has a height of 60 feet. Suppose a
  scale model of the chamber has a height of 4
  inches. What is the scale of the model?
• Write a ratio of the height of the model to the
  actual height of the statue?
• What is the scale factor?

60ft 4in
15ft 1in
1 inch 15 feet
1/180
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• Antonio is designing a room that is 20 feet long
  and 12 feet wide. Make a scale drawing of the
  room. Use the scale 0.25 inches 4 feet.
• STEP 1 Find the rooms length on the drawing
  (let x length)
• STEP 2 Find the rooms width on the drawing (let
  w width)

20 x
4 .25
Length 1.25 inches

12 x
4 .25
Width .75 inches

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• STEP 3 Make a drawing. Assume the grid below is
  ¼ inch grid paper.