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Theorem

Isoperimetric Inequality

Geometry

Among all closed curves of a given perimeter in the plane, the circle encloses the greatest area, with equality only for the circle. Known in special cases since antiquity, its full rigorous proof came much later; it generalizes to surfaces enclosing volume in higher dimensions.

Facts
Statement
For a closed curve in the plane with perimeter length L enclosing an area A, the isoperimetric inequality states that L squared is always at least 4 times pi times A, with equality holding if and only if the curve is a circle. 1
Classification
Statement Form
Inequality 1
Statement Form
Characterization Theorem 1
Connections

Has Statement Form

In Branch

Sources
1. Isoperimetric Inequality (Wikipedia)
Wikimedia Foundationlead paragraph, plane isoperimetric inequality statement
Quote, lead paragraph, plane isoperimetric inequality statement
and that equality holds if and only if the curve is a circle.
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