C++三角形面积

题目：

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 代码：
 

#include <bits/stdc++.h>
#include <cmath>
using namespace std;
 
int main() {
	double a, b, c,p,s;
	cin >> a >> b >> c;
	p = (a + b + c) / 2;
	s = p * (p - a) * (p - b) * (p - c);
	s = sqrt(s);
	cout << fixed << setprecision(4) << s << endl;
	return 0;
 
}