//Herons.C
// (c) Burt Rosenberg 1996
// This program introduces the float object, and
// compiling and linking with the math library

#include <iostream.h>
#include <math.h>

void main()
{
   float a, b, c ; // three sides of the triangle
   float s, areaSquared ;
           
   cout << "Enter a: " ;
   cin >> a ;
   cout << "Enter b: " ;
   cin >> b ;
   cout << "Enter c: " ;
   cin >> c ;
        
   // caculate the semi-perimeter
   s =  ( a + b + c ) / 2.0 ;
         
   areaSquared = s * (s-a) * (s-b) * (s-c) ;
   if ( areaSquared <= 0.0 ) 
   {
      cout << "This triangle is impossible." ;
   }
   else 
   {
      cout << "The area of this triangle is " << sqrt(areaSquared) ;
   }
   cout << endl ;

}