# Program to calculate the area between two Concentric Circles

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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