function GeoCalc(){
var Surface;
side = eval(document.circarc.side.value);
angle = eval(document.circarc.angle.value);

if((side > 0)  && (angle > 0)){

	Surface = FormatNumber((Math.PI / 180) * angle * side);
	
	document.getElementById("surface").innerHTML = "&#928; = 3.141592653589793<br />Longueur de l'arc<br />" + Surface + "  cm<br />" + FormatNumber(Surface/100) + "  m<br />";
}

}