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5-7 Scale Drawings and Scale Models.ppt

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					 5-7 Scale Drawings and Scale Models




Course 2
 5-7 Scale Drawings and Scale Models

    Warm Up
    Write each fraction in the simplest form.

          4   1             2. 9      1
       1.                             15
          48 12               135

    Convert the following measurements.
       3. 192 inches =    feet 16

       4. 18.5 feet =    inches 222

       5. 324 inches =    feet 27


Course 2
 5-7 Scale Models and Scale Drawings

    This HO gauge model train is a
    scale model of a historic train. A
    scale model is a proportional
    model of a three-dimensional
    object. Its dimensions are related
    to the dimensions of the actual
    object by a ratio called the scale
    factor. The scale factor of an HO
                            1
    gauge model train is 87 .
                                                      1
    This means that each dimension of the model is
                                                     87
    of the corresponding dimension of the actual train.


Course 2
 5-7 Scale Models and Scale Drawings


    A scale is the ratio between two
    sets of measurements. Scales can
    use the same units or different
    units. The photograph shows
    a scale drawing of the model
    train.

    A scale drawing is a proportional drawing of an
    object. Both scale drawings and scale models
    can be smaller or larger than the objects they
    represent.


Course 2
 5-7 Scale Drawings and Scale Models

           Example 1: Finding a Scale Factor

    Identify the scale factor.

                            Room   Blueprint
           Length (in.)     144          18
           Width (in.)      108      13.5

 blueprint length = 18       Write a ratio using one of the
   room length       144     dimensions.
                  = 1        Simplify.
                     8
  The scale factor is 1 .
                      8
Course 2
 5-7 Insert Drawings and Scale Models
     Scale Lesson Title Here
                          Try This: Example 1

    Identify the scale factor.

                             Model Aircraft     Blueprint
           Length (in.)           12                2
     Wing span (in.)              18                3

    blueprint length = 2           Write a ratio using one of
     aircraft length     12        the dimensions.
                      = 1          Simplify.
                          6
    The scale factor is 1 .
                        6
Course 2
 5-7 Scale Drawings and Scale Models
Example 2: Using Scale Factors to Find Unknown Lengths


    A photograph was enlarged and made into a poster.
    The poster is 20.5 inches by 36 inches. The scale
             5
    factor is 1 . Find the size of the photograph.
            poster = 5
    Think:
            photo     1
              36 = 5       Write a proportion to find the
               l   1       length l.

                 5l = 36   Find the cross products.

                 l = 7.2   Divide.

Course 2
 5-7 Scale Drawings and Scale Models
                   Example 2 Continued

    A photograph was enlarged and made into a poster.
    The poster is 20.5 inches by 36 inches. The scale
             5
    factor is 1 . Find the size of the photograph.
            poster = 5
    Think:
            photo     1
            20.5 = 5      Write a proportion to find the
             w     1      width w.

              5w = 20.5 Find the cross products.
               w = 4.1 Divide.
   The photo is 7.2 in. long and 4.1 in. wide.
Course 2
 5-7 Scale Drawings and Scale Models
                     Try This: Example 2

    Katie’s father made her a dollhouse which was
    modeled after the blueprint of their home. The
    blueprint is 24 inches by 45 inches. The scale
    factor is 1.5. Find the size of the dollhouse.
                1
             dollhouse = 1.5
    Think:
             blueprint    1
                     l = 1.5        Write a proportion to
                    45    1         find the length l.
                                    Find the cross
                     l = 45 · 1.5
                                    products.
                     l = 67.5       Multiply.

Course 2
 5-7 Scale Drawings and Scale Models
                    Try This: 2 Continued

    Ariel’s father made her a dollhouse which was
    modeled after the blueprint of their home. The
    blueprint is 24 inches by 45 inches. The scale
    factor is 1.5. Find the size of the dollhouse.
                1
             dollhouse = 1.5
    Think:
             blueprint    1
                    w = 1.5       Write a proportion
                    24   1        to find the width w.

                    w = 24 · 1.5 Find the cross products.
                   w = 36        Multiply.
   The dollhouse is 67.5 inches long and 36 inches wide.
Course 2
 5-7 Scale Drawings and Scale Models
             Example 3: Measurement Application
    On a road map, the distance between
    Pittsburgh and Philadelphia is 7.5 inches.
    What is the actual distance between the cities
    if the map scale is 1.5 inches = 60 miles?
    Let d be the actual distance between the cities.
            1.5 = 7.5
                               Write a proportion.
            60     d
           1.5 · d = 60 · 7.5   Find the cross products.
          1.5d = 450         Multiply.
          1.5d = 450
                             Divide.
           1.5    1.5
              d = 300
    The distance between the cities is 300 miles.
Course 2
 5-7 Insert Drawings and Scale Models
     Scale Lesson Title Here
                       Try This: Example 3
    On a road map, the distance between Dallas
    and Houston is 7 inches. What is the actual
    distance between the cities if the map scale is
    1 inch = 50 kilometers?
      Let d be the actual distance between the cities.
              1= 7
              50 d
                                    Write a proportion.
           1 · d = 50 · 7           Find the cross products.
            1d = 350               Multiply.
             d = 350


      The distance between the cities is 350 kilometers.


Course 2
 5-7 Scale Drawings andHere Models
     Insert Lesson Title Scale


      Assignment:
           pg. 290-291 1-13 All




Course 2

				
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