~ 1.3 ~

Making Scaled Copies

Learning Targets

  • In a pair of figures, I can identify corresponding points, corresponding segments, and corresponding angles.

  • I can describe what the scale factor has to do with a figure and its scaled copy.

Notes

Creating a scaled copy involves multiplying the lengths in the original figure by a scale factor. For example, to make a scaled copy of triangle ABC where the base is 8 units, we would use a scale factor of 4. This means multiplying all the side lengths by 4, so in triangle DEF, each side is 4 times as long as the corresponding side in triangle ABC.

Activities

3.2 Drawing Scaled Copies

Using the Geogebra Applet below ⇩ ⇩ ⇩

  1. Draw a scaled copy of either Figure A or B using a scale factor of 3.

  2. Draw a scaled copy of either Figure C or D using a scale factor of ½.

3.3 Which Operations? (Part 1)

Diego and Jada want to scale this polygon so the side that corresponds to 15 units in the original is 5 units in the scaled copy.

Diego and Jada each use a different operation to find the new side lengths. Here are their finished drawings.

  1. What operation do you think Diego used to calculate the lengths for his drawing?

  2. What operation do you think Jada used to calculate the lengths for her drawing?

  3. Did each method produce a scaled copy of the polygon? Explain your reasoning.

3.3 Which Operations? (Part 2)

Andre wants to make a scaled copy of Jada's drawing so the side that corresponds to 4 units in Jada’s polygon is 8 units in his scaled copy.

  1. Andre says “I wonder if I should add 4 units to the lengths of all of the segments?” What would you say in response to Andre? Explain or show your reasoning.

Lesson Summary

Assignments

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