I\'m making a Windows Forms application in Visual Studio 2010 Ultimate, but can\'t get the built-in Vector to work.
Microsoft says that there is a System.Windows.Vec
To find out which assembly you have to add to your references, it can be very helpful to use a tool like ILSpy (OpenSource). There you can search for the type you need, and find out in which assembly it is implemented and which namespace you have to use.
Finding out the implementing assembly can be quite difficult, and i have to do it often. I found it to be a fast method and thought it can help you in the future.