Chapter 5 of 10All chapters
Chapter 5 of 10
Similarity and scale
Why doubling a model is not doubling the paint.
Similar shapes
Similar shapes have equal angles and sides in proportion; congruent shapes are identical. Similarity is what lets you measure a tree from its shadow.
- Scale a length by k and area scales by k squared, volume by k cubed.
- That is why large animals need disproportionately thick legs.
Using proportion
Set matching sides as a ratio and solve. Most scale drawing, map and model questions are one proportion away from an answer.