Dynamic rectangle

The word "rectangle" means, literally, "right angle" (from Latin). A rectangle is a 4-sided plane figure with all right angles. Note that this definition includes squares. Move the sliders, or points B and C, to change base and height. To animate the sliders, click the play button in the lower left of the window; click again to pause the animation.
1. Will the demo ever produce squares? Where will the upper right corners of squares be? 2. It won't produce rectangles of just any size: base and height go only up to 5. But can it produce any SHAPE of rectangle? Part of the textbook Measuring the World: Mathematics for Elementary and Middle School Teachers by Susan Addington and David Dennis. Copyright 2003-9.