第六章第三十五题（几何：五边形的面积）(Geometry: area of a pentagon)

第六章第三十五题（几何：五边形的面积）(Geometry: area of a pentagon)

• 6.35（几何：五边形的面积）五边形的面积可以使用下面的公式计算：
  
  编写一个方法，使用下面的方法头来返回五边形的面积。
  public static double area(double side)
  编写一个主方法，提示用户输入五边形的边，然后显示它的面积。
  下面是一个运行示例：
  Enter the side:5.5
  The area of the pentagon is 52.044441
  6.35(Geometry: area of a pentagon)The area of a pentagon can be computed using the following formula:
  
  Write a method that returns the area of a pentagon using the following header:
  public static double area(double side)
  Write a main method that prompts the user to enter the side of a pentagon and displays its area.
  Here is a sample run:
  Enter the side:5.5
  The area of the pentagon is 52.044441
• 参考代码：

package chapter06;

import java.util.Scanner;

public class Code_35 {
    
    
    public static void main(String[] args) {
    
    
        Scanner inputScanner = new Scanner(System.in);
        System.out.print("Enter the side: ");
        double side = inputScanner.nextDouble();
        double area = area(side);
        System.out.printf("The area of the pentagon is %f", area);
    }
    public static double area(double side) {
    
    
        double area = (5 * Math.pow(side,2)) / (4 * Math.tan(Math.PI / 5));
        return area;
    }
}

• 结果显示：

Enter the side: 5.5
The area of the pentagon is 52.044441
Process finished with exit code 0