sub chk_triangle_inequality {
    # Get the points
    my ($A, $B, $C) = @_;

    # Calc the distances
    my ($AB, $AC, $BC) = (dist_2($A, $B), dist_2($A, $C), dist_2($B, $C));

    if ($AB > $AC + $BC) {
        print "ERROR: Triangle inequality fails for points ($A, $B, $C) ($AB > $AC+$BC)\n";
    }
    elsif ($AC > $AB + $BC) {
        print "ERROR: Triangle inequality fails for points ($A, $B, $C) ($AC > $AB+$BC)\n";
    }
    elsif ($BC > $AB + $AC) {
        print "ERROR: Triangle inequality fails for points ($A, $B, $C) ($BC > $AB+$AC)\n";
    }
}