Let's plot the plane ADE, by extending the front face in all directions.
Two planes are parallel if they do not intersect. We can see that plane ADE does not intersect the plane represented by the back face of the cube, so they are parallel. This is the only plane that it does not intersect. Moreover, the back face contains G. To name this plane, we can arbitrarily choose three points on that plane. One possible name can be BCG.
