If planes q and r are parallel planes. plane q contains line a. plane r contains line b. a third plane could be drawn which contains both lines a and b, then

If a third plane could be drawn which contains both lines a and b, then lines a and b must be parallel. if two lines do not intersect on the same plane, they are parallel. Furthermore, if a line is in a plane and another line is in a parallel plane, you cannot draw another plane which contains both lines a and b, only if the lines are parallel.

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