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An interactive Java Applet

Introduction:

1. Input the vertices of your polygon.
2. Press button "Close Poly" to close your polygon. Then check its simple character.
3. Press button "Chord", Then chose two points which intersect two edges of the polygon, the intersection points comprise the chord. Note that the points you chose should be a little longer than the desired chord.   
4. Press button "Center", Then chose the polar point (or projection point). Then check whether or not it is a chord.
5. Press button "Area" to get the area of polygon and that of subpolygon including the first point you input. Note the value of area is positive if the vertices are input in Counterclockwise, otherwise negative.  
6. Press button "Clear" to clear the previous polygon and draw another polygon.

Since the algorithm, you could repeat steps 3,4,5 for any times before the polygon get cleared.  

The source

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| Main Page | Introduction | History | Preliminary | Algorithms | Applet | References |