Triangle Area Methods (Exercise)

using System;

class ConsoleTests
{
    static void Main()
    {
        Console.WriteLine("Enter how you want to calculate area of triangle:");
        Console.WriteLine("1. By given three sides");
        Console.WriteLine("2. By given side and the altitude to it");
        Console.WriteLine("3. By given two sides and the angle between them in degrees");
        Console.WriteLine();
        Console.Write("Enter choice: ");
        byte choice = byte.Parse(Console.ReadLine());
        Console.WriteLine();
        double a, b, c, angle, altitude;
        if (choice == 1)
        {
            Console.Write("Enter side \"a\": ");
            a = double.Parse(Console.ReadLine());
            Console.Write("Enter side \"b\": ");
            b = double.Parse(Console.ReadLine());
            Console.Write("Enter side \"c\": ");
            c = double.Parse(Console.ReadLine());
            CalcTriangleArea(a,b,c);
            Console.WriteLine();
        }
        else if (choice == 2)
        {
            Console.Write("Enter side \"a\": ");
            a = double.Parse(Console.ReadLine());
            Console.Write("Enter altitude to \"a\": ");
            altitude = double.Parse(Console.ReadLine());
            CalcTriangleAreaAltitude(a,altitude);
            Console.WriteLine();
        }
        else if (choice == 3)
        {
            Console.Write("Enter side \"a\": ");
            a = double.Parse(Console.ReadLine());
            Console.Write("Enter side \"b\": ");
            b = double.Parse(Console.ReadLine());
            Console.Write("Enter angle between \"a\" and \"b\": ");
            angle = double.Parse(Console.ReadLine());
            CalcTriangleAreaAngle(a,b,angle);
        }
        else
        {
            Console.WriteLine("Invalid choice!");
        }


    }

    static void CalcTriangleArea(double a, double b, double c)
    {
        Console.WriteLine("Area: {0}",(a+b+c)/2);
    }

    static void CalcTriangleAreaAltitude(double z, double altitude)
    {
        Console.WriteLine("Area: {0}",(z*altitude)/2);
    }

    static void CalcTriangleAreaAngle(double x, double y, double angle)
    {
        Console.WriteLine("Area: {0}",(x*y*Math.Sin(angle))/2);
    }

}