This C program calculates and prints the area and circumference of a circle. The user enters the radius of the circle.

Basic Mathematics :

Area of a circle – π * r * r , where π = 22/7 or 3.14

Circumference of a circle = 2 * π * r

**Program:** C program to calculate area and circumference of a circle

#include<stdio.h> int main() { float r,area,cir; printf("Enter the radius of the circle:"); scanf("%f",&r); /* to allow the user to enter the radius of the circle*/ area=3.14*r*r; /* to calculate the area*/ cir=2*3.14*r; /* to calculate the circumference*/ printf("\nArea of the given circle is :%f",area); printf("\nCircumference of the given circle is :%f\n",cir); return 0; }

**Output: **

```
Enter the radius of the circle:5
Area of the given circle is :78.500000
Circumference of the given circle is :31.400000
```