math_fun.php

// $_POST method example


<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <meta name="viewport" content="width=device-width, initial-scale=1.0">
    <title>Document</title>
</head>
<body>
    <form action="index.php" method="post">
        <label>radius: </label><br>
        <input type="text" name ="radius"><br>
        <input type="submit" value="calculate">

    </form><br>
</body>
</html>

<?php


$radius = $_POST["radius"];
$circumference = null;

$circumference = 2 * pi() * $radius;
$circumference = round($circumference,2);

$area = pi() * pow($radius,2);
$area = round($area,2);

$volume = 4/3 * pi() * pow($radius,3);
$volume = round($volume,2);

echo "Circumference = {$circumference}cm <br>";
echo"Area = {$area}cm^2 <br>";
echo"Volume = {$volume}cm^3 <br>";


?>