[insert_php]
$rd = $pd = $pc = $OKVA = $NKVA= $temp= $temp1= $temp3 = $temp2 = $temp6 = 1 ;
if(isset($_POST[‘submit’])) //is-set function, when ever submit button is clicked this function executes
{
$rd = $_POST[‘RD’]; //assigning values from Form to valiables
$pd = $_POST[‘PD’];
$pc = $_POST[‘PC’];
}
unset($_POST[‘submit’]); //unsetting Submit button
$temp1 = pow($rd,2);
$temp7 = pow($pd,2);
$temp = $temp7-$temp1;
$temp8 = 3.14*$temp;
$temp9 = $temp8/4;
$OKVA = $temp9*$pc;
[/insert_php]