Answer:
The scale factor is the ratio of the length of a side of one figure to the length of the corresponding side of the other figure.
Explanation:
For example, if one triangle has side lengths of 1, 1, and 1. Then, another triangle has side lengths of 4, 4, and 4, then that means that the scale factor would be 4 because you have to multiply the first triangle by 4 to get the second triangle.