function muda_img(nome,source,submenu,state) {
	document.getElementById(nome).src = source;
	mostra_esconde(submenu,state)
}

function mostra_esconde(submenu,state) {
	document.getElementById(submenu).style.display = state;
}

function doArea(num) {
	switch(num) {
	case 0 : return (""); break;
	case 1 : var length = prompt("Por favor introduza o valor do lado do quadrado :", "");
        length = length * length;
        return (length); break;
	case 2 : var width = prompt("Por favor introduza o valor da base do triangulo (mt):", "");
        var height = prompt("Por favor introduza o valor da altura do triangulo (mt):", "");
        return (width * height / 2); break;
	case 3 : var width = prompt("Por favor introduza o comprimento do rectangulo (mt):", "");
        var height = prompt("Por favor introduza a largura do rectangulo (mt):", "");
        return (width * height); break;
	case 4 : var radius = prompt("Por favor introduza o raio do circulo (mt): ", "");
        return (Math.PI * Math.pow(radius, 2)); break;
	}
}

function CreateBookmarkLink(url, title) {
	if (window.sidebar) { // Mozilla Firefox Bookmark
		window.sidebar.addPanel(title, url,"");
	} else if( window.external ) { // IE Favorite
		window.external.AddFavorite( url, title); }
	else if(window.opera && window.print) { // Opera Hotlist
		var mbm = document.createElement('a');
	    mbm.setAttribute('rel','sidebar');
    	mbm.setAttribute('href',url);
	    mbm.setAttribute('title',title);
    	mbm.click();
	}
}