how to find area of triangle in javascript code example

Example: javascript find area of triangle

<!DOCTYPE html>
<html>


<head>
<title>HTML5 template</title>
 <link rel="stylesheet" type="text/css" href="homework14.css">

</head>



<body>
<header>Homework 14</header>

<div id="table1">

<div id="table2">

<div id="table3">

<div id="triangle">
<img src="triangle.gif">
</div>

<div id="table4">

<form>
  <label for="width">Width (b):</label>
  <input type="text" id="width" name="width">
  <label for="height">Height (h):</label>
  <input type="text" id="height" name="height">
</form>
Enter the width and height of your triangle to calculate the area


<input type="button" value="Calculate area">
</div>


</div>

<hr>

<div id="table5">

<form>
  <label for="area">The area is:</label>
  <input type="text" id="area" name="area">
</form>

</div>
</div>

</div>

</body>


</html>