Let the rectangle be ABCD with length L and width W, with midpoints of sides E,F,G,H. We are to show that EFGH is a rhombus. We may then place the figure on a graph like this with the coordinates as shown:We us the distance formula to show that all the sides of EFGH have the same length: Since EF = FG = GH = HE, EFGH is a rhombus. I didn't bother simplifying the length of the sides of rhombus EFGH, but if you want to, it's Edwin