Orateur: Minh Pham
Titre: Isoperimetric inequality
Résumé: If a planar simple closed curve is of length L and encloses an area A, then the isoperimetric inequality reads: 4\Pi A\leq L^2. The equality holds if and only if the curve is a circle. There are a lot of ways to prove this inequality, and most of rigorous proofs require calculations and basis analysis. However there are some geometric methods, which are ''less rigorous'' but more elementary. In this talk we will give such two geometric proofs, and if time allows, we will show some applications and generalisations.

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