Use the addition formula cos(u + v) = cos u cos v sin u sin v to derive the following
Chapter 9, Problem 9.2.21(choose chapter or problem)
Use the addition formula cos(u + v) = cos u cos v sin u sin v to derive the following identity for the average rate of change of the cosine function: cos(x + h) cos x h = cos x cos h 1 h sin x sin h h .
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