iPhone Duo’s aspect ratio is genius but also so simple at the same time.
It uses a 1:sqrt(2) aspect ratio for both the inside and outside display, meaning content scales perfectly between both screens.
Where else have we seen this before? A4 paper. And it’s this scaling property that allows printers to easily switch between A5, A4 and A3 sizes without issues. You can slice it in half and it has the same aspect ratio it started with.
Apple didn’t “copy” other squat foldables or invent anything new, they looked at what existed in our physical world and made a product out of it. But it raises the question of why nobody else thought of this until now. 7 years of folding phones and we were seemingly stuck with long candy-bar foldables that were struggling to grow in sales volume YoY.