lightoj - 1331 - Agent J

#include<bits/stdc++.h>
using namespace std;
int main()
{
    int test;
    cin>>test;
    for(int t=1;t<=test;t++)
    {
        double r1,r2,r3,a,b,c,s,A,B,C,area,result;
        cin>>r1>>r2>>r3;
        a=r1+r2;
        b=r2+r3;
        c=r3+r1;
        s=(a+b+c)/2;
        area=sqrt(s*(s-a)*(s-b)*(s-c));
        A=acos((a*a+c*c-b*b)/(2.0*a*c));
        B=acos((a*a+b*b-c*c)/(2.0*a*b));
        C=acos((b*b+c*c-a*a)/(2.0*b*c));
        result=area-A*r1*r1/2-B*r2*r2/2-C*r3*r3/2;
        cout<<"Case "<<t<<": "<<setprecision(9)<<fixed<<result<<endl;
    }
}