【无标题】Java求圆的面积 //Area of circle

Tags: Arithmetic CalculationsFunction //算数计算函数
Given an integer radius R, find the area of a circle.
给定一个整数半径R，求圆的面积

Area of circle = pi * radius * radius.
Where, pi is mathematical constant whose value is 3.14
圆的面积 = pi * 半径 * 半径。
其中，pi 是数学常数，其值为 3.14

Input

4

Output

50.24

Area of circle = 3.14 * 4 * 4 = 50.24

    public static void main(String[] args) {
        
        DecimalFormat df = new DecimalFormat ("0.00");
        
         Scanner sc = new Scanner(System.in);
        int r;
        r = sc.nextInt();
        double area=3.14*r*r;
        
        
        System.out.println(df.format(area));
       
    }

输出结果：