计算三角形面积

/*
功能：计算三角形面积
日期：2013-06-08
*/
#include<stdio.h>
#include<stdlib.h>
#include<math.h>

double countAreaOfTtriangle (double a,double b,double c);

int main(void)
{
   double a,b,c,area;
   printf("请输入三角形三条边的边长：");
   scanf("%lf%lf%lf",&a,&b,&c);

   area = countAreaOfTtriangle(a,b,c);
   printf("该三角形的面积为：%.3lf",area);
   system("pause");
}

double countAreaOfTtriangle (double a,double b,double c)
{
	double Area,s;
    if(a+b>c && a+c>b && c+b>a)
	{
	    s = ( a + b + c ) / 2.0 ;
		Area = sqrt(s*(s-a)*(s-b)*(s-c));
		return Area;
	}
	else
	{
	  return -1.0;
	}

}