// Function to calculate area using Heron's formula
function heronArea(float $a, float $b, float $c): float {
$s = ($a + $b + $c) / 2.0; // semi-perimeter
return sqrt($s * ($s - $a) * ($s - $b) * ($s - $c));
}
$a = 6;
$b = 9;
$c = 13;
// Check validity of triangle
if ($a + $b > $c && $a + $c > $b && $b + $c > $a) {
$area = heronArea($a, $b, $c);
echo sprintf("Area of the triangle = %.4f\n", $area);
} else {
echo "Invalid triangle sides!\n";
}
/*
run:
Area of the triangle = 23.6643
*/