The question says to use De' Moivre's Theorem and I didn't see you use it (I could be wrong), so I'll start it.
Expanding
Now compare terms with real coefficients, these terms are those that will make
Hello, sf1903!
Use de Moivre's formula and the Binomial theorem to derive a formula
that expresses as a polynomial in
DeMoivre's formula says: . .[1]
Expand the right side:
. .
. . . .
. . . .
Equate real and imaginary components:
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. . . .