Final answer:
The number used to calculate scaled copy side lengths is the scaling factor. It is the ratio that represents the relationship between the scale dimension and the measurement comparison between the scaled model and the actual length. This factor is key in resizing objects while maintaining their proportionality.
Step-by-step explanation:
The number used to calculate scaled copy side lengths is known as the scaling factor. The scaling factor is essentially the ratio of any dimension of the scaled copy to the corresponding dimension of the original figure. It helps in resizing shapes in a way that the proportions are maintained.
Let's illustrate with an example to understand the scaling factor. If you have a scaling ratio of 1:20, and you need to find the scale size for an actual length of 5.5 feet, you set up the ratio as scale/actual = 1/5.5. This means that every unit on the model represents 5.5 units in real life. To find the actual length when given a scale length, you multiply the scale length by the denominator of this ratio (which is the scale factor).
Reviewing another example, if 2 inches represent 8 feet, the scale factor would be 1 inch to 4 feet, which simplifies to a scaling factor of 1/4 when converting from actual to scale dimensions.