I.e. an aspect ratio of Sqrt(2)is the only one where the inner screen (full) and inner screen (half) match, and they seem to have tried to make the outer screen share a nearly identical aspect ratio too. I guess it's a nice consideration for more consistency in layouts for apps targeting the device. Not sure I'm particularly excited about that myself though.
but the context was "see, you can have two different apps running side by side, each with the same aspect ratio as either of the apps when run in the space of the folded screen. not only the same aspect ratio, but the same dimensions"
the whole A3/4/5 scheme is completely overblown as a feature for consumers. You format a document for A4, ok, but you wouldn't print that document A5 because the fonts would be completely shrunken. nobody does that. We use word processors to format documents for the space we have, and we don't ever print wedding invites on A3 or A4