<!DOCTYPE html>
<html>
<head></head>
<body>
<script type="text/javascript">
var a_base = 3, b_left_side = 4, c_right_side = 5;
var perimeter = a_base + b_left_side + c_right_side;
document.write("Perimeter = " + perimeter.toFixed(2) + "<br />");
var semi_perimeter = (a_base + b_left_side + c_right_side) / 2;
var area_triangle1 = Math.sqrt(semi_perimeter * (semi_perimeter - a_base) *
(semi_perimeter - b_left_side) *
(semi_perimeter - c_right_side));
document.write("Area triangle1 = " + area_triangle1.toFixed(2) + "<br />");
var b_base = 4, a_right_side = 6, angle_ab = 55;
var area_triangle2 = (a_right_side * b_base * Math.sin((Math.PI / 180) * angle_ab)) / 2;
document.write("Area triangle2 = " + area_triangle2.toFixed(2) + "<br />");
var height = 5;
b_base = 8;
var area_triangle3 = (b_base * height) / 2;
document.write("Area triangle3 = " + area_triangle3.toFixed(2) + "<br />");</script>
</body>
</html>
<!--
run:
Perimeter = 12.00
Area triangle1 = 6.00
Area triangle2 = 9.83
Area triangle3 = 20.00
-->
