In order to determine the length of cove trim required you need to know the perimeter of the room. Unfortunately, the area of a shape does not provide enough information to determine its dimensions.First of all, there is no reason to suppose that the area is rectangular as opposed to circular or triangular or some other simple or complicated shape. Even if, you know that it is a rectangle, there are infinitely many possible answers: ranging from a nearly square area to an extremely long, very thin strip.