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TS EAMCET · Maths · Complex Number

\(\sum_{r=1}^{16}\left(\sin \frac{2 r \pi}{17}+i \cos \frac{2 r \pi}{17}\right)=\)

  1. A 1
  2. B -1
  3. C \(i\)
  4. D \(-i\)
Verified Solution

Answer & Solution

Correct Answer

(D) \(-i\)

Step-by-step Solution

Detailed explanation

We have, \[ \sum_{r=1}^{16}\left(\sin \frac{2 r \pi}{17}+i \cos \frac{2 r \pi}{17}\right)=i \sum_{r=1}^{16}\left(\cos \frac{2 r \pi}{17}-i \sin \frac{2 r \pi}{17}\right) \]…