Get the angle that is the arc cosine of a complex number in CSharp

using System;/*  w  ww  .j ava 2s .  co m*/
using System.Numerics;

public class Example
{
   public static void Main()
   {
      Complex[] values = { new Complex(.5, 2), 
                           new Complex(-.3, -.8) };
      foreach (Complex value in values)
         Console.WriteLine("Cos(ACos({0})) = {1}", value, 
                           Complex.Cos(Complex.Acos(value)));
   }
}