Radio Butonlarını Kullanarak Fonksiyonları Yazdırma

<meta http-equiv="Content-Type" content="text/html; charset=utf-8" />
<form id="form1" method="POST" action="<?$PHP_SELF?>">
<table width="424" border="0" align="center" cellpadding="0" cellspacing="0" bordercolor="#333333">
  <tr>
    <th colspan="4" bgcolor="#333333" scope="col"><font color=white>Anket Çalışması </font></th>
  </tr>
  <tr>
    <td colspan="4" bgcolor="#EAEAEA"><li>Ençok hangi arama motorunu kullanıyorsunuz?</td>
    </tr>
  <tr>
    <td width="101" bgcolor="#EAEAEA">
      <label>
        <input type="radio" name="arama" id="radio" value="google" />
        </label>
    Google    </td>
    <td width="105" bgcolor="#EAEAEA"><input type="radio" name="arama" id="radio2" value="yahoo" />
      Yahoo</td>
    <td colspan="2" bgcolor="#EAEAEA"><input type="radio" name="arama" id="radio3" value="ara.com.tr" />
      Ara.com.tr</td>
    </tr>
  <tr>
    <td bgcolor="#EAEAEA">&nbsp;</td>
    <td bgcolor="#EAEAEA">&nbsp;</td>
    <td width="133" bgcolor="#EAEAEA">&nbsp;</td>
    <td width="57" bgcolor="#EAEAEA"><label>
      <input type="submit" name="button" id="button" value="Gönder" />
    </label></td>
    </tr>
  <tr>
    <td colspan="4" bgcolor="#EAEAEA">
      <p>
     
      <?php
 
    $arama=$_POST["arama"];
 
  if ($arama=="google") {
 
  echo "<br><center><b>";google();
  }elseif ($arama=="yahoo")  {
  echo "<br><center><b>";yahoo();
  }
  elseif ($arama=="ara.com.tr")  {
  echo "<br><center><b>";ara();
  }
 

  function google() {
  echo "<tr><td colspan=4 bgcolor=#CCCCCC>GOOGLE.com</td>";
  }
  function yahoo() {
  echo "<tr><td colspan=4 bgcolor=#CCCCCC>YAHOO.com</td>";
  }
 
  function ara() {
  echo "<tr><td colspan=4 bgcolor=#CCCCCC>ARA.com.tr</td>";
  }
 
  ?>
      </p>
   
    </tr> 
</table>
</form>

$arama=$_POST["arama"];