Hi,
first of all these forums are about ASP.NET, not winforms. There are dedicated forums over at www.windowsclient.net for that.
Goodway:which library should be use to call (cos, sin,..and other mathematical functions).
System.Math
Goodway:Which library is used for drawing in visual studio.
System.Drawing
Goodway:How to open and draw in Autocad.
Use google to search for the file format for autocad
Goodway:How to create and write in an excel 2003 file.
You can use VSTO for that. It's a library from Microsoft to create Office documents for example.
Goodway:How to read parameters from a file.
The File class has several methods available for you to accomplish this task.
Grz, Kris.