Complete the following method that calculates and returns the area of a triangle using Heron's formula. To use Heron's formula, first calculate half of the perimeter of the triangle, and store it in a variable named s. Then calculate s(s - a)(s - b)(s - c), where a, b, and c are the lengths of the sides of the triangle, and the values are multiplied. The area is then the square root of that value.

The perimeter of a triangle is the sum of the lengths of the sides.

public static double area(double side1, double side2, double side3) { }