5.36（Geometry：area of a regular polygon）

问题及代码：package first;import java.util.Scanner;public class MyTriangle {public static void main(String[] args) {System.out.println("请输入一个正多边形的边数和该正多边形的边长：");Scanner a = new Scanner(System.in);double s = 0;int n = a.nextInt();double side = a.nextDouble();while (true) {if (n > 0 && side > 0) {s = area(n, side);System.out.println("该正多边形的面积为：" +s);break;} else {System.out.println("输入非法，请重新输入！");}}}public static double area(int n, double side) {double s = 0;double b = n * side * side;s = (b / (4 * Math.tan((Math.PI / n))));return s;}}运行结果;