Things to Learn

  • Given a scale drawing, produce a scale drawing of a different scale.
  • Recognize that the scale drawing of a different scale is a scale drawing of the original scale drawing.
  • For the scale drawing of a different scale, compute the scale factor for the original scale drawing.

Changing Scale Factors:

  • To produce a scale drawing at a different scale, you must determine the new scale factor. The new scale
    factor is found by dividing the different (new drawing) scale factor by the original scale factor.
  • To find each new length, you can multiply each length in the original scale drawing by this new scale
    factor.
    Steps:

  1. Find each scale factor.
  2. Divide the new scale factor by the original scale factor.
  3. Divide the given length by the new scale factor (the quotient from the prior step).

New Plans

Lesson Summary
Variations of Scale Drawings with different scale factors are scale drawings of an original scale drawing.
From a scale drawing at a different scale, the scale factor for the original scale drawing can be computed without
information of the actual object, figure, or picture.
For example, if scale drawing one has a scale factor of 1/24 and scale drawing two has a scale factor of 1/72 then the scale factor relating scale drawing two to scale drawing one is:
1/72 to 1/24 = (1/72)/(1/24) = (1/72) ⋅ (24/1) = 1/3
Scale drawing two has lengths that are 1/3 the size of the lengths of scale drawing one.

Exercise and Practice