<html>
<head>
<title>Untitled Document</title>
</head>
<body>
<p>luas Lingkaran</p>
<form id="formulir" name="formulir" method="post" action="">
<table width="300"border="1">
<tr>
<td width="178">Masukan jari</td>
<td width="88"><input name="jari" type="text" id="jari"></id>
</tr>
<tr>
<td>Hasil Perhitungan Luas</td>
<td><input name="luas" type="text" id="luas"></td>
</tr>
<tr>
</table>
<p>
<input name="cari" type="button" id="cari" value="Hitung" onclick="cariluas()"/>
</p>
<form>
<script language="javascript">
function cariluas()
{
ls1=formulir.jari.value;
formulir.luas.value=22/7*ls1*ls1
}
</script>
</body>
</html>
Semoga Bermanfaat.. :)
