题目描述

写的多了容易乱了，看好条件。

样例

#include<iostream>
#include<iomanip>
using namespace std;
int main()
{
    double A,B,C,s1,s2,s3,s4,s5;
    cin>>A>>B>>C;
    s1=A*C/2;
    s2=3.14159*C*C;
    s3=(A+B)*C/2;
    s4=B*B;
    s5=A*B;
    cout<<fixed<<setprecision(3)<<"TRIANGULO: "<<s1<<endl;
    cout<<fixed<<setprecision(3)<<"CIRCULO: "<<s2<<endl;
    cout<<fixed<<setprecision(3)<<"TRAPEZIO: "<<s3<<endl;
    cout<<fixed<<setprecision(3)<<"QUADRADO: "<<s4<<endl;
    cout<<fixed<<setprecision(3)<<"RETANGULO: "<<s5<<endl;
    return 0;
}