Dido of Carthage problem (~800 BCE): max area enclosed by perimeter L is L^2/(4 pi) (circle); generalized via Lagrange-multipliers to constrained variational problems; modern Sobolev-isoperimetric.
Dido of Carthage problem (~800 BCE): max area enclosed by perimeter L is L^2/(4 pi) (circle); generalized via Lagrange-multipliers to constrained variational problems; modern Sobolev-isoperimetric.