area.php

<?php
// 7 kyu - Find the area of the rectangle!
// Find the area of a rectangle when provided with one diagonal and one side of the rectangle. If the input diagonal is less than or equal to the length of the side, return "Not a rectangle". If the resultant area has decimals round it to two places.

function area($d, $l) {
  return $d > $l ? round($l * sqrt($d ** 2 - $l ** 2),2) : 'Not a rectangle';
}

?>