Curvature and Frenet Trihedron for a Spiral Curve

① This example demonstrates the tangent, normal, and binormal vectors at each point of a 3D spiral curve, along with the moving Frenet trihedron (frame) that changes as the point moves along the curve. ② Core mathematical concepts include curvature, torsion, Frenet-Serret formulas, moving frames, orthogonality of tangent, principal normal, and binormal vectors. ③ Construction highlights: using GeoGebra commands such as CurveCartesian to define the spiral, Intersect and Point to select a moving point on the curve, Translate and Vector to construct and translate vectors, and Sphere to add auxiliary spheres for better 3D visualization; objects include t, b, a, A, c, B, u, C, C', v, A', w, d, D, e, A'_1, f, C'', g, h, A'_2, i, C''', j, etc., to build the frame components. ④ Suitable for advanced high school or university courses in calculus and differential geometry, and for mathematical visualization demonstrations.