Okay, it is
Therefor we use L'Hospital
We know that
how did you calculate the cos(3x) how is that broken down?
i know cos(2x) is cos(x)cos(x) - sin(x)sin(x)
but how did u do this one
I'm glad you ask, but what exactly is the question?
List of trigonometric identities - Wikipedia, the free encyclopedia
Use this formula for n=3
Does it help?
Using l'Hospital's Rule