title: Can't find System.Windows.Vector in C#
body: <p>I'm making a Windows Forms application in Visual Studio 2010 Ultimate, but can't get the built-in Vector to work.</p>
  
  <p>Microsoft says that there is a <a href="http://msdn.microsoft.com/en-us/library/system.windows.vector.aspx" rel="noreferrer"><code>System.Windows.Vector</code></a> in the .NET Framework 4: </p>
  
  <p>Maybe I'm making some large mistake, but Visual Studio complains about trying to use Vector in any way, and it doesn't come up in the IntelliSense autocomplete:</p>
  
  <p>The line <code>Vector v = new Vector(20, 30);</code> gives</p>
  
  <blockquote>
    <p>Compile error Error   1   The type or namespace name 'Vector' could not be found (are you missing a using directive or an assembly reference?)"</p>
  </blockquote>
  
  <p>I tried including a <code>using System.Windows</code> at the top but that didn't solve the problem.</p>
  
  <p>I went to References -> Add Reference to try to find something to add, but nothing was obvious.</p>
  
  <p>The problem may be: Also listed with <code>Vector</code> in the <a href="http://msdn.microsoft.com/en-us/library/ms599716%28v=VS.100%29.aspx" rel="noreferrer"><code>System.Windows</code></a> namespace, there are other classes like <code>Rect</code> or <code>Application</code>. I could use these as <code>System.Drawing.Rectangle</code> or <code>System.Windows.Forms.Application</code>, but <strong>none of these show up as part of some System.Windows namespace</strong></p>
  
  <p>I've tried different things for about 2 hours, and found <a href="http://social.msdn.microsoft.com/forums/en-US/csharpgeneral/thread/c32d6e27-0516-42bc-a065-e9ca99c72d78/" rel="noreferrer">this related post</a> (but Vector <strong>is</strong> part of .NET 4, so their fix doesn't seem worthwhile?) and <a href="http://social.msdn.microsoft.com/Forums/en-US/windowswic/thread/fdfff143-c1ae-41cd-bbeb-8ff6c1c879ec" rel="noreferrer">this possibly related post</a> but I do have .NET Framework 4 installed.</p>
  
  <p>Does anyone have an example of <code>Vector</code>? I know I could get a third party class, but I feel I'm missing something, and want to learn/have the solution posted for other people googling the same problem.</p>