<!DOCTYPE html>
<html>
<body>
<p>Click the button to display the cosine value of PI and 2*PI.</p>
<button onclick="myFunction()">Try it</button>
<p id="demo"></p>
<script>
function myFunction() {
var a = Math.cos(Math.PI);
var b = Math.cos(2 * Math.PI);
document.getElementById("demo").innerHTML = a + "<br>" + b;
}
</script>
</body>
</html>