11. Geometry Calculator

using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.Threading.Tasks;

namespace _11.GeometryCalculator
{
    class Program
    {
        static void Main(string[] args)
        {
            string type = Console.ReadLine().ToLower();

            if (type== "triangle")
            {
                double side = double.Parse(Console.ReadLine());
                double height = double.Parse(Console.ReadLine());
                Triangle(side, height);
            }

            else if (type == "square")
            {
                double side = double.Parse(Console.ReadLine());
                Square(side);
            }

            else if (type == "rectangle")
            {
                double side = double.Parse(Console.ReadLine());
                double width = double.Parse(Console.ReadLine());
                Rectangle(side, width);
            }

            else if (type == "circle")
            {
                double radius = double.Parse(Console.ReadLine());
                Circle(radius);
            }
        }

        static void Circle(double radius)
        {
            Console.WriteLine($"{Math.PI*radius*radius:f2}");
        }

        static void Rectangle(double side, double width)
        {
            Console.WriteLine($"{side * width:f2}");
        }

        static void Square(double side)
        {
            Console.WriteLine($"{side * side:f2}");
        }

        static void Triangle(double side, double height)
        {
            Console.WriteLine($"{(side*height)/2:f2}");
        }
    }
}