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2020 AMC 12B Question 23

AMC12 · 2020 AMC 12B

Question 23

How many integers $n \ge 2$ are there such that whenever $z_1,$ $z_2,$ $\ldots,$ $z_n$ are complex numbers such that $$
|z_1| = |z_2| = \cdots = |z_n| = 1
$$ and $$
z_1 + z_2 + \cdots + z_n = 0,
$$ then the numbers $z_1,$ $z_2,$ $\ldots,$ $z_n$ are equally spaced on the unit circle in the complex plane?
  1. $1$
  2. $2$
  3. $3$
  4. $4$
  5. $5$