Geometry · Transformations

Reflection

HSG-CO.A.5

Definition

A transformation that flips a figure over a line, creating a mirror image.

Examples

  • Reflecting triangle ABC over a line produces triangle A'B'C', a mirror image.
  • Flipping a figure over the y-axis reverses its left-right orientation.

Key rule

A reflection always flips a figure over a line, reversing its orientation.

Memory hook

Flip it over the line — mirror image.