Because if its square, the lid can easily slip inside along the diagonal. length of diagonal is greater than side of square.
3
Anonymous
Apr 11, 2016
1. Easy to roll
2. comparison to other shapes, distributes weight along sides easily :)
Anonymous
Jul 5, 2012
Minimum surface area.
3
Anonymous
Jan 9, 2014
Potholes are the spots where the road's surface has eroded away ... they are all sorts of shapes.
Manholes are round and have covers. They are round because that is the shape of the pipes that they are used to cover.