Two Perpendicular Lines Related to a Circle : PWW accompanied by GeoGebra Applets

PWW style are presented. The difference of evidence is based on various additional auxiliary constructions, which in itself is a “mathematical art” that the student can master as a result of much practice. The PWW are accompanied by GeoGebra applets containing HINT buttons that allow the student to get step-bystep help in completing the proof and understand what geometrical properties and theorems it relies on.