ABSTRACT
As opposed to curves that lie wholly in a plane (called plane curves), those curves that
occupy three dimensions are called skew curves. All three-dimensional curves must necess-
arily be expressed in parametric form:
xZ f ðtÞ
yZ gðtÞ
zZ hðtÞ:
Because there are innumerable variations of the functions f, g, and h, three-dimensional
curves can assume a wide variety of appearances. Only those curves having some
accepted significance and use are illustrated here. Many interesting and useful three-
dimensional curves can be generated simply by adding a z variation to the curves given
in the previous chapters, after they are put into parametric form.
