2: Exploring Rotations (Origin)
While the letter F is rotated here, the lesson being shown applies to all rotations. check each box separately/together to learn about the coordinates relate the Pre-Image.and Image.
http://www.maa.org/sites/default/files/images/upload_library/47/Crowe/GeoGebra_Activity_2.html by Cheryll E. Crowe, Eastern Kentucky University