Scale Factor

Suppose you have two similar figures, one larger than the other. 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.

Example:

Two similar triangles UVW and XYZ with UV = 3, VW = 4, WU = 5, and XY = 12

Here, XY UV = 12 3 =4 . So, the scale factor is 4 .

Note that when a two-dimensional figure is enlarged (dilated) by a scale factor of k , the area of the figure is changed by a factor of k 2 . In case of three-dimensional figures, when a figure is dilated by a scale factor of k , the volume is changed by a factor of k 3 .