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Geometry
Level
4
\[ \large\sum_{k=1}^{15} \textrm{cis}^{2k-1}\left( \frac{\pi}{36} \right) \]
Compute the imaginary part of the summation above.
Notation
- \( \textrm{cis }\theta = \cos \theta + i \sin\theta \).
by
Giancarlo Miragliotta