necesito un pequeño código

[Adler]

Hola

Podrías usar windwo.location.hash

Código javascript:

<?php include('categorias.php'); ?>
<input name="rad" id="1" type="radio" checked="checked" onclick="location.href='pagina1.com/index.php#1'" />
<input name="rad" id="2" type="radio" onclick="location.href='.pagina2.com/2.php#2'" />
<input name="rad" id="3" type="radio" onclick="location.href='.pagina3.com/3.php#3'" />
<input name="rad" id="4" type="radio" onclick="location.href='.pagina4.com/4.php#4'" />
 
En la p&#225;gina n.php haces esto usando window.onload
 
function funcion() {
idradio = window.location.hash;
document.getElementById(idradio) ....
}
 

Suerte