In this video I go prove the hyperbolic trigonometric identity cosh(x+y) = cosh x cosh y + sinh x + sinh y. I had proved same identity several years back in my earlier video, but that proof simply involved back-calculating that the identity was correct. In this video though, I show how to go about proving the identity without knowing the final result. I show this by illustrating that the cosh(x + y) involves a multiplication of exponents, which can also result by multiplying cosh and sinh functions together in several variations. Thus I show how to reverse a foil expansion process and ultimately obtain cosh(x+y) in terms of cosh x, cosh y, sinh x, and sinh y. This is a very interesting proof video in that I show that we need to think ahead at what we ultimately want before we begin attempting to derive an identity; so make sure to watch this video!
Watch on VidMe: https://vid.me/oDScC
Download PDF Notes: https://1drv.ms/b/s!As32ynv0LoaIhvtVnszc8jhu0oC3-Q
View Video Notes on Steemit: https://steemit.com/mathematics/@mes/video-notes-hyperbolic-trigonometric-identity-cosh-x-y
