The Applet calculates the area of an arbitrary polygon.
While the applet is executed, you can add points to the polygon by clicking on the panel. When the polygon is closed, the area can be calculated. Before the calculation starts, the whole area is calculated once, so that you can see what result will be calculated during the algorithm.
The algorithm starts by clicking on the "Start" button. For the calculation itself the Gauß-formula for trapezes is used. Therefor the polygon is divided into several trapezes, which sums can easily be summed up. If the trapeze was summed to the result, it is displayed blue, while subtracted results are red.
The applet offers different possilities. At startup (clicking on "Start") a coordinate system is shown and the options for "next" and "last" trapeze are able to use. By clicking on those buttons, you can see the progress in the calculation. The reset-button makes the coordinate system disappear.
