Lower Bound for Convex Hull Area and Universal Cover Problems
  In this paper, we provide a lower bound for an area of the convex hull of points and a rectangle in a plane. We then apply this estimate to establish a lower bound for a universal cover problem. We showed that a convex universal cover for a unit length curve has area at least 0.232239. In addition, we show that a convex universal cover for a unit closed curve has area at least 0.0879873. 
Tirasan Khandhawit, Dimitrios Pagonakis, and Sira Sriswasdi
math.MG