using System;

​

namespace UserInput

{

    public class Program

    {

        public static void Main(string[] args)

        {

            /* calculation variables */

            double a, b, c, angled, angler, a2, b2, ab, output;

            /* string variable for user input */

            string userInput;

            /* context statement */

            Console.WriteLine("To calculate the third side of a triangle, please enter two sides and an inside angle.");

            /* Accepts input from the user in string form*/

            Console.Write("Enter first side length: ");

            userInput = Console.ReadLine();

            double min = 0;

            double max = 179.999999;

            /* Try and catch statement to determine if the input is a valid number */

            /* If number is invalid, input is tried again */

            try

            {

                a = Convert.ToDouble(userInput);

            }

            catch

            {

                Console.WriteLine("Please enter a valid number");

                userInput = Console.ReadLine();

                a = Convert.ToDouble(userInput);

            }

​

            Console.Write("Enter second side length: ");

            userInput = Console.ReadLine();

            /* Try and catch statement to determine if the input is a valid number */

            /* If number is invalid, input is tried again */

            try

            {

                b = Convert.ToDouble(userInput);

            }

            catch

            {

                Console.WriteLine("Please enter a valid number.");

                userInput = Console.ReadLine();

                b = Convert.ToDouble(userInput);

            }

​

            Console.Write("Enter an inside angle. Values above 180 not accepted and will be treated as maximum for a triangle: ");

            userInput = Console.ReadLine();

            /* Try and catch statement to determine if the input is a valid number */

            /* If number is invalid, input is tried again */

            try

            {

                angled = Convert.ToDouble(userInput);

                /* clamps value to 179.999999 */

                angled = Math.Min(Math.Max(angled, min), max);

            }

            catch

            {

                Console.WriteLine("Please enter a valid number.");

                userInput = Console.ReadLine();

                angled = Convert.ToDouble(userInput);

            }

​

            /* converts to radians */

            angler = angled * (Math.PI / 180);

            /* squared values for the final expression */

            a2 = Math.Pow(a, 2);

            b2 = Math.Pow(b, 2);

            /* a x b pre-calculation */

            ab = a * b;

            /* final expression */

            c = a2 + b2 - 2 * ab * Math.Cos(angler);

            /* square root of final expression for side length */

            output = Math.Sqrt(c);

            Console.WriteLine("The length of the third side is {0}", output);

        }

    }

}