#include <stdio.h>
#include <conio.h>
#include <math.h>

int main()
{
	float a,b,c;
	float dientich, chuvi, p;
	
	do
	{
	printf("\t Hay nhap a= ");
	scanf("%f",&a);
	}
	while (a<0);
	
	do
	{
	printf("\t Hay nhap b= ");
	scanf("%f",&b);
	}
	while (b<0);
	
	do
	{
	printf("\t Hay nhap c= ");
	scanf("%f",&c);
	}
	while (c<0);
	
	if ((a==0)||(b==0)||(c==0)) printf("\t ==> KHONG thoa man dieu kien tao thanh TAM GIAC");
	else
	{
		if ((a+b>c)&&(a+c>b)&&(b+c>a)) 
		{
			printf("\t ==> Thoa man dieu kien tao thanh TAM GIAC");
			chuvi=a+b+c;
			p=chuvi/2;	
			dientich=sqrt(p*(p-a)*(p-b)*(p-c));
			printf("\n\t Chu vi cua TAM GIAC = %.2f",chuvi);
			printf("\n\t Dien tich cua TAM GIAC = %.2f",dientich);
		}
		else printf("\t ==> KHONG thoa man dieu kien tao thanh TAM GIAC");	
	}
	getch();
	return(0);
}