Answer
a)$\overline{BC}$, $\overline{EH}$, $\overline{FG}$
b) Because they are coplanar
c) plane ADH $\parallel$ plane BCG
d) $\overline{AB}$, $\overline{EF}$
Work Step by Step
a) $\overline{BC}$, $\overline{EH}$ & $\overline{FG}$ do not intersect $\overline{AD}$
b) Skew lines are noncoplanar. $\overline{FE}$ and $\overline{CD}$ are in the plane that runs diagonally through the cube, so they are coplanar.
c) The planes that form the front and back of the cube do not intersect and are parallel.
d) The planes that form the sides of the cube are parallel, so segments on one of those planes are parallel to the other plane.
