Area of Figures

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

namespace _09.Area_of_Figures
{
    class Program
    {
        static void Main(string[] args)
        {
            string figureType = Console.ReadLine();
            double area = 0.0;

            switch (figureType)
            {
                case "square":
                    double a = double.Parse(Console.ReadLine());
                    area = a * a;
                    break;
                case "rectangle":

                    a = double.Parse(Console.ReadLine());
                    double b = double.Parse(Console.ReadLine());
                    area = a * b;
                    break;
                case "circle":
                    double r = double.Parse(Console.ReadLine());
                    area = Math.PI * r * r;
                    break;
                case "triangle":
                    a = double.Parse(Console.ReadLine());
                    double h = double.Parse(Console.ReadLine());
                    area = (a * h) / 2;
                    break;
            }
            Console.WriteLine($"{area:F3}");
        }
    }
}