5th root of 2 in the ratio of the heights ... virtually exactly.
5th root of 2 = 1.0218971486541166782344801347833
280 / 274 = 1.0218978102189781021897810218978
Difference = 0.00000067
This I did not find and it is amazing !!!!!!
However on the link you posted you have Petire's data giving us an angle of 212.00 degrees at Giza .This is incorrect as the uncorrected measurements gives us 211.92 while the corrected measurements gives us 211.897
But the 5th root of 2 ... mind boggling.