Geometric Descriptive: Straight Lines and Line Projections

This lecture covers the concept of straight lines in geometric descriptive, including the purity of lines, sketches of parallel lines, and the traces of lines in space. It also discusses the projections of lines, such as horizontal, frontal, and profile lines, and their properties. The lecture further explores the relative positions of two lines, coplanar lines, and the perpendicularity of lines to projection planes.