01  #include<stdio.h>
02  #include<math.h>
03  
04  int main()
05  {
06  
07  int side;
08  float area;
09  
10  printf("nEnter the Length of Side : ");
11  scanf("%d", &side);
12  
13  area = (float)(sqrt(3)*(side * side))/4;
14  
15  printf("nArea of Equilateral Triangle : %.2f", area);
16  return 0;
17  }

 
 OUTPUT :
 
 Enter the Length of Side : 5
 Area of Equilateral Triangle : 10.83