function mudaImagem(){
	img = new Array(5);
	img[0] = "<img src=\"images/img1.jpg\" width=\"685\" height=\"254\"/>";
	img[1] = "<img src=\"images/img2.jpg\" width=\"685\" height=\"254\"/>";
	img[2] = "<img src=\"images/img3.jpg\" width=\"685\" height=\"254\"/>";
	var num = (Math.random()*2);
	var num2 = Math.round(num)
	document.getElementById("imagem").innerHTML = img[num2];
}