Planes, Normals and Intersections

① This example demonstrates the geometric relationships between two planes in 3D space, their normal vectors, and their line of intersection, providing an interactive visualization of plane intersections. ② Core mathematical concepts include plane normals, the intersection line of two planes, vector operations, and angle relationships in spatial geometry. ③ Construction highlights: using GeoGebra commands IntersectPath to find the intersection line, Point to create key points, Vector to construct normals, and Angle to measure the dihedral angle; objects include planes a and b, points A, B, C, D, E, vectors u and v, angles α and β, and auxiliary lines c, d, e. ④ Suitable for high school or college solid geometry instruction, helping students understand the algebraic and geometric connections between plane equations, normals, and intersection lines, and useful for classroom demonstrations in spatial vectors and analytic geometry.