Solved: Exercises 79 81 will help you prepare for the
Chapter 4, Problem 4.8.86(choose chapter or problem)
Exercises 79 81 will help you prepare for the material covered in the first section of the next chapter. The exercises use identities, introduced in Section 4.2, that enable you to rewrite trigonometric expressions so that they contain only sines and cosines: In Exercises 79 81, rewrite each expression by changing to sines and cosines. Then simplify the resulting expression.
Unfortunately, we don't have that question answered yet. But you can get it answered in just 5 hours by Logging in or Becoming a subscriber.
Becoming a subscriber
Or look for another answer