函数用法题解

#include <bits/stdc++.h>
using namespace std;
void tra (double a,double b,double c)
{
	double s,p;
	p=(a+b+c)/2;
	s=sqrt(p*(p-a)*(p-b)*(p-c));
	cout<<fixed<<setprecision(2)<<s;
}
int main()
{
	double a,b,c;
	cin>>a>>b>>c;
    
	tra(a,b,c);
 return 0;
}