2026-07-072026-07-07http://salesiana.dossiersoluciones.com/handle/123456789/122416Often some interesting or simply curious points are left out when developing a theory. It seems that one of them is the existence of an upper bound for the fraction of area of a convex and closed plane area lying outside a circle with which it shares a diameter, a problem stemming from the theory of isoperimetric inequalities. In this paper such a bound is constructed and shown to be attained for a particular area. It is also shown that convexity is a necessary condition in order to avoid the whole area lying outside the circle.6 pages, 5+2 figuresGeneral Mathematics52A10,52A38text