After skimming through some info on Euler's formula, I can substitute sinn= (e^in - e^(-in)) / 2i, I'm confused as to what you are trying to state, could you perhaps elaborate? How exactly did you derive with r = exp(i)/2?
I believe we haven't learned that yet unfortunately, however I have determined that the series is absolutely convergent via the comparison test. What r value can i use so
|r| < 1
, involved with the numerator as well? :S
From what I can tell, you can change the lower index to n=1, but I assume I will have to check for convergence first, if the series does converge, I can move ahead with this method, if not, I will need an alternative.
Homework Statement
\sum_{n=1}^{\infty}\frac{sinn}{2^n}
Homework Equations
Definition of a geometric series:
\sum_{n=0}^{\infty}x^n=\frac{1}{1-x}
The Attempt at a Solution
Basically I can use the geometric series idea and implement it into the denominator of the question (i.e. sub x=2 into...