The point on the x-axis controls the vertical line x=a, where a is the x-intercept. Move the point to display the vertical line you need. It is possible to hide the controlling point using option 3 in the Actions menu (press Menu-1-3).
There are no teacher or student notes provided with this template file.
Are there other simple templates that you would find useful? If so please send an email to Christopher Rath (firstname.lastname@example.org).