C Program to find area and circumference of circle

#include<stdio.h>

int main()
{
int rad;
float PI=3.14,area,ci;

printf("Enter radius of circle: ");
scanf("%d",&rad);

area = PI * rad * rad;
printf("Area of circle : %f ",area);

ci = 2 * PI * rad;
printf("Circumference : %f ",ci);

return(0);
}

Output :

Enter radius of a circle : 1
Area of circle : 3.14
Circumference  : 6.28

Explanation of Program :

In this program we have to calculate the area and circumference of the circle. We have following 2 formulas for finding circumference and area of circle.

Area of Circle = PI * R * R

and

Circumference of Circle = 2 * PI * R

In the above program we have declared the floating point variable PI whose value is defaulted to 3.14.We are accepting the radius from user.

printf("Enter radius of circle: ");
scanf("%d",&rad);