In Exercises 9799, prove that the equations are
Chapter 8, Problem 99(choose chapter or problem)
In Exercises 9799, prove that the equations are identities. (These identities appear in Trigonometry and Double Algebra, by August DeMorgan, published in 1849.)cos 2u 1/(1 tan 2u tan u)
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