Consider the diagram. planes m and n intersect at line d. lines a, b, and e are on plane m. line a is vertical and forms a right angle with line d. line b is diagonal and goes up and to the right. line e is at the top of the plane and is close to being horizontal. line c is on plane n and is goes slightly up and to the right. why are lines e and c skew lines? they lie in different planes and will never intersect. they lie in the same plane but will never intersect. they lie in different planes but will intersect if a plane is drawn to contain both lines. they lie in different planes and will be parallel if a plane is drawn to contain both lines.