<SCRIPT LANGUAGE="JavaScript">

<!-- Begin
function doArea(num) {
switch(num) {
case 0 : return (""); break;
case 1 : var length = prompt("Seitenlänge des Quadrats:", "");
length = length * length;
return (length); break;
case 2 : var width = prompt("Breite des Dreiecks", "");
var height = prompt("Höhe des Dreiecks", "");
return (width * height / 2); break;
case 3 : var width = prompt("Breite des Rechtecks:", "");
var height = prompt("Höhe des Rechtecks", "");
return (width * height); break;
case 4 : var radius = prompt("Radius des Kreises", "");
return (Math.PI * Math.pow(radius, 2)); break;
case 5 : var radius = prompt("Radius der Sphäre", 0);
return (4 * Math.PI * (Math.pow(radius, 2))); break;
}
}
// End -->
</script>

<center>
<form name=calcarea>
Berechnen Sie die Fläche eines:
<select name="shape" size="1" onChange="this.form.area.value = doArea(this.selectedIndex);">
<option> ...
<option value="square">Quadrat
<option value="triangle">Dreieck
<option value="rectangle">Rechteck
<option value="circle">Kreis
<option value="sphere">Sphäre
</select>
= <input type=text name=area size=10>
</form>
</center>

<p><center>
<font face="arial, helvetica" size="-2">Free JavaScripts provided<br>
by <a href="http://javascriptsource.com">The JavaScript Source</a></font>
</center>