Curves I
摘要
The topic of curves can fill books. Even the definition of the term curve can be debated for hours. We will not do that. We are only interested in plane curves and space curves, we do not consider pathological exceptions. Plane curves and space curves have a beginning and an end, a length and a curvature, they can intersect or be represented differently. These are suggestive terms and facts that actually mean exactly what one imagines.