表达式4: "C" left parenthesis, "t" , right parenthesis plus .4 "N" left parenthesis, "t" , right parenthesis cosine left parenthesis, "f" left parenthesis, "t" , right parenthesis , right parenthesis plus .4 left parenthesis, "T" left parenthesis, "t" , right parenthesis times "N" left parenthesis, "t" , right parenthesis , right parenthesis sine left parenthesis, "f" left parenthesis, "t" , right parenthesis , right parenthesisCt+.4Ntcosft+.4Tt×Ntsinft
00
定义域t最小值：
less than or equal to "t" less than or equal to≤t≤
定义域t最大值： 2 pi2π
4
Unit tangent & normal for Frenet frame:
5
表达式6: "T" left parenthesis, "t" , right parenthesis equals StartFraction, "C" prime left parenthesis, "t" , right parenthesis Over StartAbsoluteValue, "C" prime left parenthesis, "t" , right parenthesis , EndAbsoluteValue , EndFractionTt=C′tC′t
6
表达式7: "N" left parenthesis, "t" , right parenthesis equals StartFraction, "T" prime left parenthesis, "t" , right parenthesis Over StartAbsoluteValue, "T" prime left parenthesis, "t" , right parenthesis , EndAbsoluteValue , EndFractionNt=T′tT′t
