import java.util.Scanner;
class switch_case{
    public static void main(String[] args) {
        int jawab;
        Scanner scan = new Scanner(System.in);
        System.out.println("[1] Luas Segitiga");
        System.out.println("[2] Luas Lingkaran");
        System.out.println("[3] Luas Peregi\n");
        System.out.print("Masukkan Pilihan Anda = ");
        jawab = scan.nextInt();

        switch (jawab) {
            case 1:
                segitiga();
                break;
            case 2:
                lingkaran();
                break;
            case 3:

            default:
                break;
        }


    }

    static void segitiga(){
        float alas, tinggi, luas;
        Scanner scan = new Scanner(System.in);
        System.out.println("Luas Segitiga");
        System.out.print("Masukkan Alas = ");
        alas = scan.nextInt();
        System.out.print("Masukkan Tinggi = ");
        tinggi = scan.nextInt();
        luas = (alas*tinggi)/2;
        System.out.print("Luas Segitiga = "+luas);
    }

    static void lingkaran(){
        final double phi = 3.14;
        double r, luas;
        System.out.println("Luas Lingkaran");
        System.out.print("Masukkan jari-jari = ");
        Scanner scan = new Scanner(System.in);
        r = scan.nextInt();
        luas = phi*r*r;
        System.out.println("Luas Lingkaran = "+luas);
    }
}