Answer :

#include<stdio.h>  //header file contains the function,decleraction and macro defination of key words used in code.

int main ()

{

float area,pi=3.14,radius; //adressing the variables

printf("Enter the radius of  circle\t"); //output 

scanf("%f",&radius);  //stores the input from the user

area=pi*radius*radius; //formula

printf("\n***************************\n\n"); //output desgin

printf("Area of Circle is %.2f\t\n\n",area);//output

printf("***************************\n\n"); //output desgin

}

Output :