// calculate its cosine
    double result = Math.cos( Math.toRadians(degrees) );

Function Results as Arguments

One function call is nested inside another. The value that the nested function returns becomes the parameter for the outer function.

double result = Math.cos( Math.toRadians(degrees) );

This is perfectly fine, and is a reasonable way to write the code, as long as the inner function returns a value that is correct for the outer function. In fact, you could nest the function calls within println():

// calculate its cosine and print the result
System.out.println("cosine: " + Math.cos(  Math.toRadians(degrees) ) );

It is a matter of taste, sometimes, how much put in one statement. Your goal should be to make the logic clear, not to save typing.