Geometry · Similarity & Right Triangles

Scale Factor

HSG-SRT.A.2

Definition

The ratio of corresponding lengths in similar figures, used to enlarge or reduce.

Teach it

Where it is taught, with guided notes, practice, homework, an exit ticket and an interactive Teacher Deck.

Examples

  • If a figure's sides double, the scale factor is 2.
  • A scale factor of 1/2 shrinks a figure to half its original size.

Key rule

A scale factor greater than 1 enlarges; less than 1 reduces.

Memory hook

The multiplier that resizes similar figures.