Question Number 33584 by abdo imad last updated on 19/Apr/18
$${find}\:{the}\:{value}\:{of}\:\:\sum_{{n}=\mathrm{1}} ^{\infty} \:\:\frac{\left(\mathrm{1}+{i}\right)^{{n}} \:{cos}\left({n}\theta\right)}{\mathrm{2}^{{n}} }\:. \\ $$
find-the-value-of-n-1-1-i-n-cos-n-2-n-