Symmetric: A function is symmetric when it possesses a particular type of balance or equality. In the case of even symmetry, this balance occurs across the y-axis.
Mirror Image: A mirror image refers to an identical reflection on opposite sides of an axis or plane. In terms of even symmetry, both sides of the graph are mirror images of each other.
Axis: An axis is a reference line used for measurement and comparison. The y-axis specifically runs vertically through a coordinate plane and serves as a central point for determining symmetry in functions.