C++ 代码

#include <iostream>
using namespace std;
const double P = 3.14159;
int main()
{
    double a,b,c;
    double s[4];
    cin >> a >> b >> c;
    s[0] = a*c / 2;
    s[1] = P * c*c;
    s[2] = (a + b)*c /2;
    s[3] = b*b;
    s[4] = a*b;
    printf("TRIANGULO: %.3lf\n",s[0]);
    printf("CIRCULO: %.3lf\n",s[1]);
    printf("TRAPEZIO: %.3lf\n",s[2]);
    printf("QUADRADO: %.3lf\n",s[3]);
    printf("RETANGULO: %.3lf\n",s[4]);
    return 0;
}