C Programming Code Examples C > Mathematics Code Examples Program to find area and circumference of circle Program to find area and circumference of circle 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. #include<stdio.h> int main() { int rad; float PI = 3.14, area, ci; printf("\nEnter radius of circle: "); scanf("%d", &rad); area = PI * rad * rad; printf("\nArea of circle : %f ", area); ci = 2 * PI * rad; printf("\nCircumference : %f ", ci); return (0); }