Prove the change of variable formula, i. e., suppose that g e c([a, b), and f: [c间→ [a, b] is differentiable with f' e r(c, d), then prove that s(e)

Skew lines(segments) are lines(segments) in 3 dimensions that do not intersect the given segment and are not parallel to it.  ae, bf, eg, and fh are your skew segments.  i hope that : )