​x
 
<html>
<head>
<script type="text/javascript">
function check()
  {
  document.getElementById("radio1").checked=true
  }
function uncheck()
  {
  document.getElementById("radio1").checked=false
  }
</script>
</head>
<body>
​
<form>
<input type="radio" id="radio1" />
<input type="button" onclick="check()" value="Check radio button" />
<input type="button" onclick="uncheck()" value="Uncheck radio button" />
</form>
​
</body>
</html>
​