## C# program to find the area of a circle :

In this post, we will learn how to find the area of a circle in *C sharp*. We will take the radius as input from the user and calculate the *area*. With this program, you will learn how to take user inputs in *C sharp* and how to do mathematical calculations.

### Formula to find the area of a circle:

Below formula is used to calculate the circle area:

`π * r * r`

Where, *r* is the radius and *π* is the mathematical constant Pi.
We will take the value of radius from the user as input. For *π*, we can either define a variable and assign it upto a specific decimal place or we can use *Math.PI* constant that is available in *C#*.

### C# program:

Below is the complete program to calculate circle area in *C#*:

```
using System;
public class Program
{
public static void Main()
{
int radius;
double area;
Console.WriteLine("Enter the value of radius: ");
radius = int.Parse(Console.ReadLine());
area = Math.PI * radius * radius;
Console.WriteLine("Area of the circle is : "+ Math.Round(area,2));
}
}
```

## Explanation:

*radius*is an*int*value to keep the radius of the circle.*area*is a*double*to save the area of the circle.- We are using
*int.Parse*to parse the user input number i.e. the radius. - The final area is stored in the double
*area* - Finally, we are writing down the area of the triangle.

### Sample output:

```
Enter the value of radius:
10
Area of the circle is :314.16
```