A figure is said to have a line symmetry when:
We can fold a picture in half such that the right and left halves match exactly
The two halves are mirror images of each other
A figure is said to have a line symmetry when we can fold a picture in half such that the right and left halves match exactly or in other words when the two halves are mirror images of each other. The line about which the figure is symmetric is called the line of symmetry.