java编程题五边形的面积解题答案

liang183

package nameyu;import java.util.Scanner;public class Test {

    /**

     * @param args

     */

    public static void main(String[] args) {

        // TODO Auto-generated method stub

        Scanner input=new Scanner(System.in);

        System.out.print("Enter the lenght from the center to a vertex:");

        double r=input.nextDouble();

        double s=2*r*Math.sin(Math.PI/5);

        double area=(5*Math.pow(s, 2))/(4*Math.tan(Math.PI/5));

        System.out.printf("The area of the pentagon is%4.2f ",area);

    }

    }