I have a hard time wrapping my head around the triangle cake, too..Is the pound cake just plain, no icing, no nothing, and then after you slice it on the diagonal, you ice it?
Or do you slice it horizontally, ice it, put it back together, then slice it on the diagonal? My only familiarity with pound cake is one I made that had thirteen eggs in it.
You slice it on the diagonal after you frost the layers (obviously you don’t frost the top until after you cut it otherwise you’ll end up with sticky fingers). You don’t cut it in regular slices. You cut it on the long side. You’ll end up with about four slices.