Lines and planes in space

Study lines and planes in three-dimensional space using vectors, parameters and normal directions. This precalculus extension focuses on directly checkable examples: writing equations, testing membership, distinguishing parallelism from containment, and identifying perpendicular or skew configurations. Single-select and multiselect tasks include geometric reasoning and error analysis, with worked solutions that verify every conclusion by substitution or a dot product. General systems of several equations and advanced intersection algorithms are reserved for later study.