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AP EAMCET · Maths · Complex Number

If z=cos6°+isin6°, then n=120Imz2n-1=

  1. A 0
  2. B -1
  3. C -34sin6°
  4. D 34sin6°
Verified Solution

Answer & Solution

Correct Answer

(D) 34sin6°

Step-by-step Solution

Detailed explanation

∑n=120z2n-1=z+z3+z5+…+z39 Now, z=cos6°+isin6°=ei6° Substitute the value in the series, ∑n=120z2n-1=ei6°+ei18°+ei30°+…+ei39×6° =ei6°1+ei120+ei240+……+ei2280…