8th Grade · Geometry
Scale Factor
8.G.A.4
Definition
The ratio of a length in the image to the corresponding length in the original figure. It tells how much a dilation enlarges or reduces a figure.
Examples
- A side of 4 becomes 8 → scale factor = 8/4 = 2.
- k > 1 enlarges; k = 1 keeps the same size; 0 < k < 1 shrinks.
Key rule
Scale factor compares the image's length to the original's length.
Memory hook
How many times bigger or smaller.