We consider the problem of approximating a convex gure in the plane by a pair (r; R) of homothetic (that is, similar and parallel) rectangles with r C R. We show the existence of such a pair where the sides of the outer rectangle are at most twice as long as the sides of the inner rectangle, thereby solving a problem posed by Polya and Szeg}o. If the n vertices of a convex polygon C are given as a sorted array, such an approximating pair of rectangles can be computed in time O(log2 n).