#include<stdio.h>
#include<math.h>
int main()
{
    double a,b,c,s,area;
    a = 3.67;
    b = 5.43;
    c = 6.21;
    s = (a + b + c)/2;
    area = sqrt(s*(s-a)*(s-b)*(s-c));
    printf("a=%f\tb=%f\tc=%f\t",a,b,c);
    printf("area=%f\n",area);
}