; then the point-track containing
and parallel to
will intersect every member of
.
43.3 A theorem analogous to those of [43.2] also holds for two families of point-tracks. Let
be any point-track and let
; then the point-track containing
and parallel to
will intersect every member of
.
43.3 A theorem analogous to those of [43.2] also holds for two families of point-tracks. Let
be any point-track and let