Distance allows you to find the distance between any two points on any two equations. There are two ways to draw a distance line:

While tracing hit 'D' (not case sensitive) at the point you would like to start your line. At this point an anchor is placed at the point you hit 'D'. Continue tracing towards your second desired point. You will see a line from where you first hit 'D' to where the tracing cross-hair currently is and the distance of that line displayed in the upper left corner of the graph. You can select another equation by pressing the up and down arrows, or continue tracing. Once you have reached the end-point for your distance line hit 'D' again. A final line will be drawn from your start point to the finish point and the distance displayed in the upper left corner of the graph.

Select "Distance" from the graph menu. You will be prompted for starting and ending x values for the line, and one or two equations. If you select one equation, the line will go from the first x value on the selected equation, to the second x value on the selected equation. If you select two equations, the start of the line will be at the first x value on the first equation to the second x value on the second equation. When you hit 'Ok' the line will be drawn on the graph.

To remove the distance line do one of the following:

Press 'D' while tracing

Select "Distance" from the graph menu

You may have only one distance line per graph tab at any one time.