1. Computing Actual Areas from a Scale Drawing
Lesson 19
Computing Actual Areas from a Scale Drawing

2. Review
What is the difference between scale and scale factor?

3. Examples 1–3: Exploring Area Relationships
Use the diagrams below to find the scale factor and then find the area of each figure.
Example 1
Scale factor: _________
Actual Area = ______________
Scale Drawing Area = ________________
Ratio of Scale Drawing Area to Actual Area: _________

4. Scale factor: _________ Actual Area = ______________
Example 2
Scale factor: _________
Actual Area = ______________
Scale Drawing Area = ________________
Ratio of Scale Drawing Area to Actual Area: _________

5. Scale factor: _________ Actual Area = ______________
Example 3
Scale factor: _________
Actual Area = ______________
Scale Drawing Area = ________________
Ratio of Scale Drawing Area to Actual Area: _________

7. Why do you think it is squared as opposed to cubed or something else
Why do you think it is squared as opposed to cubed or something else? How might you use this information I working with scale drawings? Suppose a rectangle has an area of 12 square m. If it is enlarged by a scale factor of three, what area would you predict the enlarged rectangle to have based on what you just concluded?