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191 geometry/manhole.cover.p




Description

This article is from the Puzzles FAQ, by Chris Cole chris@questrel.questrel.com and Matthew Daly mwdaly@pobox.com with numerous contributions by others.

191 geometry/manhole.cover.p


Why is a manhole cover round?

geometry/manhole.cover.s

It will not fall into the hole, even if rotated, tipped, etc.
It gives maximal area for a given amount of material.
It does not have to be carried, but can be rolled.
Human beings are roughly round in horizontal cross section.
Orientation of the cover with the access hole is not of concern.
Orientation of the access hole with the ladder in the pipe below is not
of concern.

 

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