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> Incidentally, this is the real reason manholes were round.

This doesn't pass the sniff test to me. A manhole lid fits loosely in its frame, and is simply cast. The round shape is used ecause that way the lid cannot fall into the hole (frame is a slightly narrower diameter than the lid is in any orientation)



But that works with equilateral polygons as well. How would a square lid fall into a smaller square hole?


Diagonally, because the hole is 1.4 times wider diagonally than the cover is on each side


Me dumb. The hole would have to be much smaller.


Diagonally. The length of a side is considerably shorter (1/sqrt(2) times shorter, actually) than the diagonal.




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