// re4(7).cpp
/* this program calculates the area of a triangle, using heron\'s formula */
#include<iostream>
#include<stdio.h>
#include<conio.h>
#include<math.h>
inline int tricon (float de,float dr,float dt)
{
if ( (de+dr>dt) && (dr+dt>de) && (de+dt>dr) )
{return 25;}
else {}
return 0;
}
inline float triare (float se,float sr,float st)
{
int ss=(se+sr+st)/2;
int ree=0;
ree=sqrt((ss-se)*(ss-sr)*(ss-st));
return ree;}
using namespace std;
int main()
{
float s1,s2,s3;
puts(" please enter the sides of the triangle\\n ");
cin>>s1>>s2>>s3;
if (tricon(s1,s2,s3)==25)
{cout<< triare(s1,s2,s3);}
else {cout<< " this is not a proper triangle ";}
}