De Moivre's Theorem
https://www.aplustopper.com/de-moivres-theorem/
https://sites.google.com/site/aplustoppernotes/de-moivre-s-theorem
http://cbsetuts.blogspot.in/2018/02/de-moivres-theorem.html
(1) If n is any rational number, then (cos θ + i sin θ)n = cos nθ + i sin nθ.
(2) If z = (cos θ1 + i sin θ1) (cos θ2 + i sin θ2) (cos θ3 + i sin θ3)………… (cos θn + i sin θn)
then z = cos (θ1 + θ2 + θ3 + ……… + θn) + i sin (θ1 + θ2 + θ3 + ……… + θn)
where θ1 + θ2 + θ3 + ……… + θn ∈ R.
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