While the letter F is triple reflected about three parallel lines, the lesson being shown applies to all similar reflections. check each box separately/together to learn how the coordinates relate the mirror (the y-axis here for ease of learning.) What is different?
[url]http://www.maa.org/sites/default/files/images/upload_library/47/Crowe/GeoGebra_Activity_6.html[/url] by Cheryll E. Crowe, Eastern Kentucky University