Lecture
This lecture covers the concept of quadrants and bisector planes in descriptive geometry. It explains how the two projection planes divide space into four regions called quadrants and how bisector planes are the loci of equidistant points in space. The lecture also demonstrates the construction of projections for different geometric figures and the determination of points on bisector planes. Additionally, it introduces the use of Geogebra for geometric constructions and provides examples of determining quadrants and intersections with bisector planes.