Stage 29 · Spatial Vectors & Solid Geometry
29.4.4 Finding a Dihedral Angle with Normal Vectors
29.4 Measuring Angles with Vectors — Line–Plane and Dihedral Angles
Point 4 of 5
29.4.4 Finding a Dihedral Angle with Normal Vectors
Core ideaCompute cosθ between the two normal vectors, then read the picture to decide whether to keep that angle or take its supplement.
Module goal. Use the angle formulas for direction and normal vectors to turn abstract spatial angles into coordinate calculations, working out angles between lines, between a line and a plane, and dihedral angles in a systematic way.