21. In the case of differential curves, the curvature vector is a normal vector of special interest. 22. The vector is e . g . the normal vector of a plane mirror in three dimensions. 23. This means that at some junction between two pieces we will have normal vectors pointing in opposite directions. 24. The direction of a reflected ray is determined by the vector of incidence and the surface normal vector . 25. In effect, a point rotated around its normal vector will not change the way it reflects light. 26. Horocycles correspond to the motion of the normal vectors of a horosphere on the upper half-plane. 27. In rendering, also the normal vector \ boldsymbol { n } to the surface is often needed. 28. Dividing this vector by its length yields a unit normal vector to the parametrised surface at a regular point: 29. The relationship of these, of corse would be to calculate the Normal Vector of the curvature of the surface. 30. They are normal vector can be expressed as a linear combination of two future directed null vectors, normalised by:
