รบกวนถามการเรียกใช้ Method ที่อยู่ภายใน Class เดียวกันหน่อยครับ C#

using System;
namespace Mounova
{
    class Chanatza
    {
        static void Main()
        {
            Boonchan ee = new Boonchan();
            ee.Insert();

        }
    }
        public class Boonchan
        {
            private const double PL = 3.14;
            
            private double Radius;
            private double Base;
            private double Height;

            public Boonchan()
            {
                this.Radius = 1;
            }
            public Boonchan(double radius)
            {
                this.Radius = radius;
            }
            public double Triangle()
            {
                double radius = this.Radius;
                return (1 / 2) * Base * Height;
            }
            public double Circle()
            {
                double radius = this.Radius;
                return PL * Radius * Radius;
            }
            public void Insert()
            {

                Console.WriteLine("=====================");
                Console.WriteLine("1.Circle");
                Console.WriteLine("2.Triangle");
                Console.WriteLine("=====================");

                
                

                Console.WriteLine("Please select choice: ");
                int choice = int.Parse(Console.ReadLine());


                if (choice == 1)
                {
                    Console.Write("Please,key Radius: ");
                    this.Radius = double.Parse(Console.ReadLine());
                    Circle();

                }


                else if (choice == 2)
                {
                    Console.Write("Please,key Height: ");
                    this.Height = double.Parse(Console.ReadLine());
                    Console.Write("Please,key Base: ");
                    this.Base = double.Parse(Console.ReadLine());
                    Triangle();

                }
                else
                {
                    Console.Write("It not 1 or 2 select again");

                }
                
                Output();

            }
            void Output()
            {
                Console.WriteLine("Circle has area: " + Circle());
                Console.WriteLine("Triangle has area: " + Triangle());
                Console.Write("Do you want play again<Y/N>: ");
                string again = Console.ReadLine();
                if ((again == "y") || (again == "Y"))
                Insert();
                else
                {

                }
            }

        }
    }

                    Console.Write("Please,key Height: ");
                    this.Height = double.Parse(Console.ReadLine());
                    Console.Write("Please,key Base: ");
                    this.Base = double.Parse(Console.ReadLine());
                    Triangle();
                  //  ตรงนี้ทำไมบรรทัดTriangle(); ไม่ไปเรียก 
            public double Triangle()
            {
                double radius = this.Radius;
                return (1 / 2) * Base * Height;
            }