his can be used to illustrate the symmetry of the graph of [i]y[/i] = cos([i]x[/i]). The graph is symmetric about the y-axis. This is illustrated by showing that whenever a point ([i]t[/i], cos([i]t[/i])) is on the graph, the point ([i]-t[/i], cos([i]t[/i])) is also on the graph.
