Primitive Notions and Propositions: Lines, Planes, and Geometric Construction

① This example demonstrates the construction and verification of the most basic primitive notions in Euclidean geometry — points, lines, and planes — and their incidence propositions. ② Core mathematical concepts include straight lines, planes, points, segments, parallelism, perpendicularity, and the foundational axioms of spatial geometry. ③ Construction highlights: the GeoGebra commands Line (to create lines r and s) and Plane (to create plane a) are used together with text objects texto1, texto2 and points A, B, C, D to label and illustrate the elementary geometric objects. ④ Suitable for high‑school geometry lessons, introductory college geometry courses, and geometric construction practice, serving as a visual teaching aid or self‑study demonstration.