3D Geometric Demonstration of the Theorem of Three Perpendiculars

This GeoGebra applet visually demonstrates the Theorem of Three Perpendiculars using 3D solid geometry constructions. The model includes key geometric elements such as planes, oblique lines, perpendiculars, and projections. Utilizing polygons, segments, and angle measurement tools, it clearly illustrates the property that if a line in a plane is perpendicular to the projection of an oblique line p