C++ 代码

#include<iostream>
#include<cstdio>
using namespace std;
int main(){
    double a,b,c,x1,x2,x3,x4,x5;
    double pi=3.14159;
    scanf("%lf%lf%lf",&a,&b,&c);
    x1=a*c/2;
    x2=pi*c*c;
    x3=(a+b)*c/2;
    x4=b*b;
    x5=a*b;
    printf("TRIANGULO: %.3lf\n",x1);
    printf("CIRCULO: %.3lf\n",x2);
    printf("TRAPEZIO: %.3lf\n",x3);
    printf("QUADRADO: %.3lf\n",x4);
    printf("RETANGULO: %.3lf\n",x5);
    return 0;
}