程序来计算刻在正方形上的圆的面积

给定正方形的一面。任务是找到正方形内切圆的面积。

例子：

Input : a = 8
Output : Area of an inscribed circle: 50.24

Input : a = 12.04
Output : Area of an inscribed circle: 113.795

给定一个正方形，即正方形的所有边均等长，并且所有四个角度均为90度。下图描绘了正方形中的内接圆。

正方形中的内接圆的属性：

• 正方形内切圆的直径等于正方形边的长度。
• 通过至少一个对圆或正方形的度量，可以计算出内切圆的正方形的面积和周长。
• 正方形的中心和圆的中心在同一点。
• 当至少给出一个圆或正方形的度量时，可以计算出圆的周长和面积。

  Formula to find the area of an inscribed circle: $\frac{\Pi}{4} a^{2}$

  where a is the side of a square in which a circle is inscribed.

  How does the formula works?
  Assume a is the side of a square and we know that a square has 4 sides.

  Area of a circle = $\Pi r^{2}$

  where r is the radius of a circle and area of a square = a²

  Therefore, the area of an inscribed circle in a square = $\Pi r^{2}$
  Now, put r = a / 2
  So, the area of an inscribed circle in a square = $\frac{\Pi}{4} a^{2}$

  C++

  // C++ Program to find the area of 
  // an inscribed circle in a square.
  #include
  #define PI 3.14
  using namespace std;
    
  // Function to find area of an 
  // inscribed circle in a square.
  float areaOfInscribedCircle(float a)
  {
      return ( PI / 4 ) * a * a;
  }
    
  // Driver's code
  int main()
  {
      float a = 8;
        
      cout << "Area of an inscribed circle: "
           << areaOfInscribedCircle(a);
             
      return 0;
  }

  Java

  // Java Program to find the area of 
  // an inscribed circle in a square.
  import java.io.*;
    
  class GFG {
        
      static double PI = 3.14;
        
      // Function to find area of an 
      // inscribed circle in a square.
      static double areaOfInscribedCircle(float a)
      {
          return ( PI / 4 ) * a * a;
      }
    
      // Driver code
      public static void main (String[] args)
      {
          float a = 8;
        
          System.out.println("Area of an inscribed"
          + " circle: " + areaOfInscribedCircle(a));
      }
  }

  Python 3

  # Python Program to find the area of 
  # an inscribed circle in a square.
        
  PI = 3.14
        
  # Function to find area of an 
  # inscribed circle in a square.
  def areaOfInscribedCircle(a):
      return ( PI / 4 ) * a * a
    
  # Driver code
  a = 8
  print("Area of an inscribed circle:",
    round(areaOfInscribedCircle(a), 2))

  C#

  // C# Program to find the 
  // area of an inscribed 
  // circle in a square.
  using System;
    
  class GFG 
  {
      static double PI = 3.14;
        
      // Function to find area  
      // of an inscribed circle
      // in a square.
      static double areaOfInscribedCircle(float a)
      {
          return (PI / 4 ) * a * a;
      }
    
      // Driver code
      public static void Main ()
      {
          float a = 8;
        
          Console.WriteLine("Area of an inscribed" + 
                                       " circle: " +
                          areaOfInscribedCircle(a));
      }
  }
    
  // This code is contributed
  // by anuj_6

  输出：

  Area of an inscribed circle:50.24