Final answer:
Lines of symmetry are the lines that divide a shape into two equal, mirror-image halves.
Step-by-step explanation:
In mathematics, the lines of symmetry for a shape are the lines that divide the shape into two equal, mirror-image halves. To find the lines of symmetry, you can look for any lines that can be drawn through the shape and result in two identical halves.
For example, a square has four lines of symmetry: two vertical lines and two horizontal lines. On the other hand, a triangle has three lines of symmetry: one vertical line and two diagonal lines.
It is important to note that not all shapes have lines of symmetry. Some irregular shapes, such as a star or a crescent, do not have any lines of symmetry.