In order to use the functions in the `java.lang.Math`

class in your Java program, you will need to import the class. This can be done using the `import`

statement at the beginning of your program:

`import java.lang.Math;`

Once you have imported the `Math`

class, you can access its functions using the following syntax: `Math.functionName()`

. For example, to use the `sqrt()`

function, which calculates the square root of a number, you can write the following code:

`double squareRoot = Math.sqrt(4.0); // squareRoot will be 2.0`

You can find a list of all the functions available in the `Math`

class in the Java documentation: https://docs.oracle.com/en/java/javase/11/docs/api/java.base/java/lang/Math.html.