Crear cuenta
private int getInteger(String s) {
int x;
try {x = Integer.parseInt(s);
} catch (NumberFormatException ex) {
x = 0;ex.printStackTrace(System.out);
}return x;
}protected void processRequest(HttpServletRequest request, HttpServletResponse response)
throws ServletException, IOException {
response.setContentType("text/plain;charset=UTF-8");
String sa = request.getParameter("a");
String sb = request.getParameter("b");
String sc = request.getParameter("c");
int a = getInteger(sa);
int b = getInteger(sb);
int c = getInteger(sc);
float p = (a + b + c) / 2;
double area = Math.sqrt(p * (p - a) * (p - b) * (p - c));
try (PrintWriter out = response.getWriter()) {
out.println(area);
}}<!DOCTYPE html>
<html>
<head>
<title>Test</title>
<meta charset="UTF-8">
<meta name="viewport" content="width=device-width, initial-scale=1.0">
</head>
<body>
<form id="form-test">
<table>
<tr><td>Lado "A" <input type="number" id="a" /></td></tr>
<tr><td>Lado "B" <input type="number" id="b" /></td></tr>
<tr><td>Lado "C" <input type="number" id="c" /></td></tr>
<tr>
<td>
<button type="submit">Consultar</button>
</td>
</tr>
</table>
</form>
<script src="https://cdnjs.cloudflare.com/ajax/libs/jquery/3.3.1/jquery.min.js"></script>
<script>
$("#form-test").submit(function (event) {
event.preventDefault();
$.post("CalcularAreaTriangulo", {
a: $("#a").val(),
b: $("#b").val(),
c: $("#c").val()
}, function (text) {
alert(text);
});
});
</script>
</body>
</html>