2.16（几何：六边形面积）编写程序，提示用户输入六边形的边长，然后显示它的面积。计算六边形面积的公式是： 面积 = 。
这里的s就是边长。下面是一个运行示例：
Enter the length of the side : 5.5
The area of the hexagon is 78.5918
2.16Geometry: area of a hexagon) Write a program that prompts the user to enter the side of a hexagon and displays its area. The formula for computing the area of a hexagon is area = .
where s is the length of a side. Here is a sample run:
Enter the length of the side : 5.5
The area of the hexagon is 78.5918
参考代码：
package chapter02; import java.util.Scanner; public class Code_16 { public static void main(String[] args) { double LengthHexagonSide,AreaHexagon; System.out.print("Enter the length of the side : "); Scanner LenSideInput = new Scanner(System.in); LengthHexagonSide = LenSideInput.nextDouble(); AreaHexagon = 3 * Math.pow(3,0.5) / 2 * Math.pow(LengthHexagonSide,2); System.out.println("The area of the hexagon is " + AreaHexagon); LenSideInput.close(); } } 结果显示： Enter the length of the side : 5.5 The area of the hexagon is 78.59180539343781 Process finished with exit code 0