Redirect based on radio button option

As of now it appears that the only way to redirect a form to another specific form based on the users selection of radio button option is to redirect to an external php file. The php file then watches for a specific query string and redirects based on that.

$agree = $_GET['agree'];
        switch ($agree)
        {
             case “radio-option-a“:
             header(“Location: domain.com/new-form“);
        }

Is this correct?

We have a developers license and usually get support via email but this seems like a good topic to put out in the open.