Medieval cubits also varied. You do have to calibrate to the King's Chamber cubit, which seems defensible. But the numbers do check out: 2phi²/(5pi/3) = 1.0000

Medieval cubits also varied. You do have to calibrate to the King's Chamber cubit, which seems defensible. But the numbers do check out: 2phi²/(5pi/3) = 1.000015 is pretty trippy, no matter how you slice it. Likewise 5sqrt(6)pi/3-2sqrt(2) = 9.997. There's no denying the ancients would be impressed with that sort of thing. Maybe even Newton, too. Of course, none of this proves the Egyptians knew about any of it. Probably the lesson for us is that numerical coincidences are way more common and less significant than we are inclined to think. [Also: pi ~ 3.14159265...]