01  #include <stdio.h>
02  
03  int main()
04  {
05   int side,perimeter;
06  
07   float apothem; // min distance from center to egde
08  
09   float area;
10  
11   printf("Enter the value of side : ");
12   scanf("%d",&side);
13  
14   printf("Enter the value of Apothem : ");
15   scanf("%f", &apothem);
16  
17   perimeter=7*side;
18  
19   area = (perimeter*apothem)/2;
20  
21   printf("Area of the Regular Heptagon = %.2f n", area);
22   return 0;
23   }

 OUTPUT :
 Enter the value of side : 7
 Enter the value of Apothem : 7.4
 
 Area of the Regular Heptagon =  181.30