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Calculate the argument and modulus for the number complex A:
you know
$\displaystyle 0< \frac{\theta}{2} <\pi$
so,
$\displaystyle if \ \ \pi<\theta <2\pi$
then $\displaystyle 2cos(\frac{\theta}{2}+\pi)>0$
$\displaystyle (1+e^{i\theta})^n=(2cos(\frac{\theta}{2}+\pi))^ne^ {ni(\frac{\theta}{2}+\pi)}$
$\displaystyle if \ \ 0<\theta <\pi$ (it's easier than the precedent )
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