ALPHA DIVISION

Question 83

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Question

The value of

\displaystyle\sum_{n=0}^{\infty}\frac{\cos(n)}{2^n}

can be expressed as

\dfrac{a-b\cos(1)}{c-d\cos(1)}

, where

a

b

c

, and

d

are positive integers that do not all share a common prime factor. Find

a+b+c+d

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