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<h1>The Calculator</h1>
<h3>Version 1.3</h3>
<p>Important: Use the radian equivalent to the number when getting cos, sin and tan.</p>
<hr>
<h2>Simple</h2>
<form action="" method="post">
<input name="first" type="text" size="6" maxlength="10">
<select name="method1">
    <option value="add" selected>Add</option>
    <option value="sub">Subtract</option>
    <option value="multi">Multiply</option>
    <option value="div">Divide</option>
</select>
<input name="second" type="text" size="6" maxlength="10">
<br><br>
<input name="submit1" type="submit" value="Calculate">
</form>
<?php
// Get variables from POST:
if (isset($_POST['submit1'])  ) {
$submit1 = $_POST['submit1'];

$method1 = $_POST['method1'];

$first = $_POST['first'];
$second = $_POST['second'];
switch ($method1) {
        case "add": $ans = $first + $second;
        break;
        case "sub": $ans = $first - $second;
        break;
        case "multi": $ans = $first * $second;
        break;
        case "div": $ans = $first / $second;
        break;
    }

$ans = number_format($ans, 2, ',', ' ');
echo "<p>The answer is $ans</p>";

}

?>
<hr>
<h2>Advanced</h2>

<form action="" method="post">
<input name="number" type="text" size="6" maxlength="10">
<select name="method2">
    <option value="cos">Get cosine</option>
    <option value="sin">Get sine</option>
    <option value="tan">Get tangent</option>
    <option value="decbin">Decimal to binary</option>
    <option value="bindec">Binary to decimal</option>
    <option value="dechex">Decimal to hexadecimal</option>
    <option value="hexdec">Hexadecimal to decimal</option>
    <option value="deg2rad">Degree to radian</option>
    <option value="rad2deg">Radian to degree</option>
</select>
<br>
<br>
<input name="submit2" type="submit" value="Calculate">
</form>
<?php

if (isset($_POST['submit2'])) {


$method2 = $_POST['method2'];

$number = $_POST['number'];

    switch ($method2) {
        case "cos": $ans = cos($number);
        break;
        case "sin": $ans = sin($number);
        break;
        case "tan": $ans = tan($number);
        break;
        case "decbin": $ans = decbin($number);
        break;
        case "bindec": $ans = bindec($number);
        break;
        case "dechex": $ans = dechex($number);
        break;
        case "hexdec": $ans = hexdec($number);
        break;
        case "deg2rad": $and = deg2rad($number);
        break;
        case "rad2deg": $ans = rad2deg($number);
        break;
    }
echo "<p>The answer is $ans</p>";
}
?>