Intuitive Notion of Line Symmetry and Plane Symmetry Line symmetry Line symmetry, or just symmetry, occurs when two halves of a figure mirror each other across a line. The line of symmetry is the line that divides the figure into two mirror images. A simple test to determine if a figure has line symmetry is to fold the figure along the supposed line of symmetry and see if the … [Read more...] about Intuitive Notion of Line Symmetry and Plane Symmetry