using System;

​

public class Program

{

    static decimal pi = 3.14159M;

    public static void Main()

    {

        start:

        Console.WriteLine("Please enter [1] to find the surface area of a cone.");

        Console.WriteLine("Please enter [2] to find the surface area of a cylinder.");

        Console.WriteLine("Please enter [3] to find the surface area of a sphere.");

        string choice = Console.ReadLine();

        Console.WriteLine(" ");

        if (choice == "1")

        {

            Console.WriteLine("Please enter a value for the Radius");

            decimal r = decimal.Parse(Console.ReadLine());

            Console.WriteLine("Please enter a value for the Height");

            decimal h = decimal.Parse(Console.ReadLine());

            Console.WriteLine(" ");

            Console.WriteLine("The surface area of your cone is: " + Cone(r, h));

        }

        else if (choice == "2")

        {

            Console.WriteLine("Please enter a value for the Radius");

            decimal r = decimal.Parse(Console.ReadLine());

            Console.WriteLine("Please enter a value for the Height");

            decimal h = decimal.Parse(Console.ReadLine());

            Console.WriteLine(" ");

            Console.WriteLine("The surface area of your Cylinder is: " + Cylinder(r, h));

        }

        else if (choice == "3")

        {

            Console.WriteLine("Please enter a value for the Radius");

            decimal r = decimal.Parse(Console.ReadLine());

            Console.WriteLine(" ");

            Console.WriteLine("The surface area of your Sphere is: " + Sphere(r));

        }

        else 

        {

            Console.WriteLine("Please enter a valid choice!");

            Console.WriteLine("Press [ENTER] to go back to the start");

            Console.ReadLine();

            Console.Clear();

            goto start;

        }

        Console.WriteLine("Would you like to restart the program? [Y/N]");

        string restart = Console.ReadLine();

        if (restart == "Y" || restart == "y")

        {

            Console.Clear();

            goto start;

        }

    }

​

    static private decimal Cone(decimal r, decimal h)

    {

        double r2 = (double)r * (double)r;

        double h2 = (double)h * (double)h;

        double slant = Math.Sqrt(r2 + h2);

        return pi * r * r + pi * r * (decimal)slant;

    }

​

    static private decimal Cylinder(decimal r, decimal h)

    {

        decimal pi2 = 2 * pi;

        decimal r2 = r * r;

        decimal piR = pi2 * r2;

        decimal piRH = pi2 * r * h;

        return piR + piRH;

    }

​

    static private decimal Sphere(decimal r)

    {

        return 4 * pi * r * r;

    }

}