关于可展曲面的两点注记

Two Notes on Developable Surface

探讨了满足条件(a'(u),b(u),b'(u))=0的直纹面r(u,ν)=a(u)+νb(u)为可展曲面的合理性,验证了只有一族直母线是可展曲面的必要但不充分条件.然后给出可展曲面的又一等价条件.

In this article, the rationalization which ruled surface satisfied is developable surface is discussed and that only bunch of ruling of a ruled surface is essential condition but not full condition of developable surface are verified, then an equivalent condition of developable surface is set out.