Let $z = 2 e^{10 \pi i/21} $ and $w = e^{\pi i/7}$. Then what is \[|(z+w)^6|,\]the magnitude of $(z+w)^6$?
As follows:
(Can't help feeling there's probably a simpler way!)
Here's a simpler way!
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Better method Alan, but you've still missed the 2 at the front of z.
You are right! But I'll leave it to someone else to include that!