Line over which a figure in a plane is reflected.

### Symbol

- A reflection is denoted by the letter
*r*. - The line of reflection, ℓ, is denoted by r
_{ℓ}. - If the line of reflection in the Cartesian plane is the
*x*-axis, it is denoted by r. If the line of reflection is the_{x-axis}*y*-axis, it is denoted by r_{y-axis.}

### Property

In a reflection *r *with a line of reflection *ℓ*, the image of a point *C *is the point *C*‘ such that the segment *CC*’ is perpendicular to the line of reflection *ℓ*, and the midpoint *O* of *CC*’ is on the reflection line *ℓ*.

### Example

*Line of reflection d.*