<!DOCTYPE html>
<html>
<body>

<h3>A demonstration of how to access a Radio Button</h3>

Radio Button: <input type="radio" id="myRadio">

<p>Click the "Try it" button to check the radio button.</p>

<button onclick="myFunction()">Try it</button>

<script>
function myFunction() {
    var x = document.getElementById("myRadio");
    x.checked = true;
}
</script>

</body>
</html>