The Java class library is huge. We will not cover it all today. In
fact, the remaining eight classes will focus mostly on the class
library. However, I do want to take this opportunity to look
briefly at one useful class in the library,
`java.lang.Math.`

This is a class which contains static
methods for performing many standard mathematical operations like
square roots and cosines. You will need it for many of this weeks
exercises.

The `Math`

class contains several dozen static
methods. Recall that to use a static method from a class, you just
prefix its name with the name of the class followed by a period.
For instance

`double x = Math.sqrt(9.0);`

You never need to instantiate the `Math`

class
directly. (In fact you can't. The `Math()`

constructor
is declared private.)