This demonstration allows you to explore the behavior of the perimeter of the midpoint polygon for a rectangle as the lengths of the rectangle's sides change. After you click on the button labelled "Demo", two windows should appear.
In one of the windows, labelled "Controls", the perimeters and their ratio are displayed, and two variables, "a" and "b", are defined. In the other window, a rectangle with sides of length 2a and 2b is drawn, as is its midpoint polygon.
On the right side of the controls window, there are two series of buttons, one to control the value of a, and one for b. By clicking on these buttons, you can change the value of the variables. Alternatively, you may directly set their value by typing it in the small boxes in the middle of the rows of buttons.