GeometryCalculator

using System;

namespace _11Problem_GeometryCalculator
{
    class Program
    {
        static void Main(string[] args)
        {
            string figure = Console.ReadLine();
            CalculateAndPrintTheArea(figure);
        }

        static void CalculateAndPrintTheArea(string figure)
        {
            double area = 0.0;

            switch (figure)
            {
                case "triangle":
                    double triangleSide = double.Parse(Console.ReadLine());
                    double triangleHeight = double.Parse(Console.ReadLine());
                    area = (triangleSide * triangleHeight) / 2;
                    break;

                case "square":
                    double squareSide = double.Parse(Console.ReadLine());
                    area = squareSide * 4;
                    break;

                case "circle":
                    double circleRadius = double.Parse(Console.ReadLine());
                    area = Math.PI * (circleRadius * circleRadius);
                    break;

                case "rectangle":
                    double rectangleWidth = double.Parse(Console.ReadLine());
                    double rectangleHeight = double.Parse(Console.ReadLine());
                    area = rectangleHeight * rectangleWidth;
                    break;
            }

            Console.WriteLine($"{area:f2}");
        }
    }
}