Solution of Dido’s problem using variations

Isoperimetric problems are an important class of variational problems. They represent problems in which the optimization is subject to one or more constraints. The term “isoperimetric problems” likely does not make you think of optimization with constraints. However, they have been given this name due to their origin, a problem from antiquity. Given a fixed perimeter, the problem asked to find the geometric figure that encloses the largest possible area. The answer is, perhaps intuitively, the circle. The techniques developed in this section show how to use calculus of variations to answer this and other similar questions. We begin by presenting a variant of this problem.