Question

Write a program to calculate the area of a circle, given the radius of the circle. Hint - use pi = acos(-1) as pi != 3.1416 input format input consists of a single integer r denoting the radius of the circle. Output format output the area of the circle rounded to 4 decimal places

Answer 1

#include<stdio.h>

#include<math.h>

int main() {

       float r,pi = 'put the pi value here';

       scanf("%f",&r);

       printf("%0.4f\n",pi * r * r)

       return 0;

}