Classes & Class Libraries: Best practices and other imponderables.

[KBConsole]

This thread has for goal to gather the POV and experience of fellow VB.NET programmers regarding the creation of Classes and Class Libraries.
Any questions on the subject or links to documentation are welcome as long as it follows the forum's rules of course.

I'll start with a question that may seem simple to many but I still haven't found an answer to.
Assuming I am to create a Class Library for geometrical shapes and I want to store Pi as a constant which of the following would be best:


Jokes aside I highly prefer the first option to avoid calling unrequired classes everytime but I'm not sure my approach would be well viewed.