Area Of Figures

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

namespace ConsoleApp19
{
    class Program
    {
        static void Main(string[] args)
        {
            string inputFigure = Console.ReadLine().ToLower();

            if (inputFigure == "square")
            {
                double area = double.Parse(Console.ReadLine());

                Console.WriteLine($"{ area* area:f3}");
            }
            else if (inputFigure == "rectangle")
            {
                double areaOfRectangle = double.Parse(Console.ReadLine());
                double perimeterOfRectangle = double.Parse(Console.ReadLine());

                Console.WriteLine($"{areaOfRectangle * perimeterOfRectangle:f3}");
            }
            else if (inputFigure == "circle")
            {
                double r = double.Parse(Console.ReadLine());
                Console.WriteLine($"{r * r * Math.PI:f3}");
            }
            else if(inputFigure == "triangle")
            {
                double width = double.Parse(Console.ReadLine());
                double height = double.Parse(Console.ReadLine());
                Console.WriteLine($"{width * height /2:f3}");
            }
        }
    }
}