double x,
                left = 0,
                right = 1,
                eps = 1e-4;
            do
            {
                x = (left + right) / 2;
                if ((Math.Cos(x) - x) * (Math.Cos(left) - left) < 0)
                    right = x;
                else
                    left = x;
            } while (Math.Abs(right - left) < eps);
            Console.WriteLine("Корень равен " + x);
            Console.ReadKey();