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Which Math is Right?

On a farm, why are silo's tall and round? (Note: this question assumes you know what a silo is, given they have been used for grain storage as long ago as ancient Greece in the late 8th century BC.)

Ivan Pfalser (Caney, KS) claims the reason is structural. That is, a circle is "the most efficient configuration to carry the stress produced by an internal load." He continues by arguing that a square-shaped silo would be overstressed by the internal pressure of a load, resulting in bending of the sides (into arcs) or buckling.

But, I can hear other mathematicians arguing that the reason lies in the fact that a circle maximizes area for a given perimeter. In turn, this saves on construction costs.

So, which mathematical reason is correct? Or, could it be that both responses are the same, just in different clothing? Your thoughts...

Source: Adapted from D. Feldman's A World of Imponderables, 1992, p. 549