Luas

#include <iostream>
using namespace std;

float luas_persegi_panjang (float a, float b){
    return a*b;
}

float luas_segitiga (float a, float b){
    return (a*b / 2);
}

float luas_lingkaran (float r){
    return 3.14 * (r* r);
}

float jajar_genjang (float alas, float tinggi){
    return (alas * tinggi);
}

float kubus (float s){
    return 6 * (s * s);
}

int main (){
    float a, b, alas, tinggi, r;
    int pilih;
    cout << "Menghitung Luas" << endl;
    cout << "Menu : " << endl;
    cout << "1. Persegi panjang" <<endl;
    cout << "2. Segitiga " << endl;
    cout << "3. Lingkaran " <<endl;
    cout << "4. Jajar genjang" << endl;
    cout << "5. Kubus" << endl;
    cout << "Pilih : " ; cin >> pilih;
    switch(pilih){
        case 1:
            cout << "Persegi panjang " << endl;
            cout << "Panjang : "; cin >> a;
            cout << "Lebar : "; cin >> b;
            cout << "Hasil : " << luas_persegi_panjang(a,b);
            break;
        case 2:
            cout << "Segitiga " << endl;
            cout << "Alas : "; cin >> a;
            cout << "Lebar : "; cin >> b;
            cout << "Hasil : " << luas_segitiga(a,b);
            break;
        case 3:
            cout << "Lingkaran" << endl;
            cout << "Jari-jari : "; cin >> r;
            cout << "Hasil : " << luas_lingkaran(r);
            break;
        case 4:
            cout << "Jajar genjang" << endl;
            cout << "Alas : "; cin >> alas;
            cout << "Tinggi : "; cin >> tinggi;
            cout << "Hasil : " << jajar_genjang(alas,tinggi);
            break;
        case 5:
            cout << "Kubus" << endl;
            cout << "jari-jari : "; cin >> r;
            cout << "Hasil : " << kubus(r);
            break;
        default :
            cout << "Masukkan rumus !";
            break;

    }
}