<!-- Begin
function circle(form,changed) {
with (Math) {
var area = form.area.value;
var diameter = form.diameter.value;
var circumference = form.circumference.value;
if (changed == "area") {
var radius = sqrt(area / PI);
diameter = 2 * radius;
circumference = PI * diameter;
}
if (changed == "diameter") {
area = PI * (diameter / 2) * (diameter / 2);
circumference = PI * diameter;
}
if (changed == "circumference") {
diameter = circumference / PI;
area = PI * (diameter / 2) * (diameter / 2);
       }
form.area.value = area;
form.diameter.value = diameter;
form.circumference.value = circumference;
  }
}
var toDegrees = 360 / (Math.PI * 2);
var toRadians = (Math.PI * 2) / 360;
//  End -->