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Program to calculate the area between two Concentric Circles
• Last Updated : 15 Feb, 2019

Given two concentric circles with radius X and Y where (X > Y). Find the area between them.

You are required to find the area of the green region as shown in the following image:

Examples:

Input : X = 2, Y = 1
Output : 9.42478

Input : X = 4, Y = 2
Output : 37.6991

## Recommended: Please try your approach on {IDE} first, before moving on to the solution.

Approach:

The area between the two given concentric circles can be calculated by subtracting the area of the inner circle from the area of the outer circle. Since X>Y. X is the radius of the outer circle.

Therefore, area between the two given concentric circles will be:

π*X2 - π*Y2

Below is the implementation of the above approach:

## C++

 // C++ program to find area between the // two given concentric circles    #include using namespace std;    // Function to find area between the // two given concentric circles double calculateArea(int x, int y) {     // Declare value of pi     double pi = 3.1415926536;        // Calculate area of outer circle     double arx = pi * x * x;        // Calculate area of inner circle     double ary = pi * y * y;        // Difference in areas     return arx - ary; }    // Driver Program int main() {     int x = 2;     int y = 1;        cout << calculateArea(x, y);        return 0; }

## Java

 // Java program to find area between the // two given concentric circles import java.io.*;    class GFG  {        // Function to find area between the // two given concentric circles static double calculateArea(int x, int y) {     // Declare value of pi     double pi = 3.1415926536;        // Calculate area of outer circle     double arx = pi * x * x;        // Calculate area of inner circle     double ary = pi * y * y;        // Difference in areas     return arx - ary; }    // Driver code public static void main (String[] args)  {     int x = 2;     int y = 1;     System.out.println (calculateArea(x, y)); } }    // This code is contributed by jit_t.

## Python 3

 # Python3 program to find area between   # the two given concentric circles     # Function to find area between the  # two given concentric circles  def calculateArea(x, y):         # Declare value of pi      pi = 3.1415926536        # Calculate area of outer circle      arx = pi * x * x         # Calculate area of inner circle      ary = pi * y * y         # Difference in areas      return arx - ary     # Driver Code x = 2 y = 1    print(calculateArea(x, y))     # This code is contributed  # by shashank_sharma

## C#

 // C# program to find area between the // two given concentric circles using System;    class GFG  {        // Function to find area between the // two given concentric circles static double calculateArea(int x, int y) {     // Declare value of pi     double pi = 3.1415926536;        // Calculate area of outer circle     double arx = pi * x * x;        // Calculate area of inner circle     double ary = pi * y * y;        // Difference in areas     return arx - ary; }    // Driver code public static void Main ()  {     int x = 2;     int y = 1;     Console.WriteLine(calculateArea(x, y)); } }    // This code is contributed by Code_Mech.

## PHP



Output:

9.42478

Time Complexity: O(1)

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