function show_form(areaShape) {
	if(areaShape) {
		hide_forms();
		document.getElementById("formula_" + areaShape).style.display = "block";
	}
}

function hide_forms() {
	document.getElementById("formula_Square").style.display = "none";
	document.getElementById("formula_Rectangle").style.display = "none";
	document.getElementById("formula_Oval").style.display = "none";
	document.getElementById("formula_Circle").style.display = "none";
	document.getElementById("formula_Area").style.display = "none";
}