8th Grade · Geometry
Rigid Motion
8.G.A.2
Definition
A transformation that preserves distances and angles, producing a congruent image. Translations, reflections, and rotations are rigid motions; dilations are not.
Examples
- A translation slides a figure without changing its size or shape.
- A dilation is NOT rigid — its size changes.
Key rule
Rigid motions always produce a congruent image.
Memory hook
Slides, flips, and turns — size and shape stay the same.