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TS EAMCET · Maths · Complex Number

For \(n \in \mathbf{N}\), If \(A_n=\cos \left(\frac{\pi}{2^n}\right)+i \sin \left(\frac{\pi}{2^n}\right)\), then \(\left(A_1 A_2 A_3 A_4\right)^4=\)

  1. A \(\frac{-1-i}{\sqrt{2}}\)
  2. B 1
  3. C 0
  4. D \(\frac{1-i}{\sqrt{2}}\)
Verified Solution

Answer & Solution

Correct Answer

(D) \(\frac{1-i}{\sqrt{2}}\)

Step-by-step Solution

Detailed explanation

It is given that, \(A_n=\cos \left(\frac{\pi}{2^n}\right)+i \sin \left(\frac{\pi}{2^n}\right), n \in \mathbf{N}=e^{i\left(\frac{\pi}{2^n}\right)}\) \(\therefore\left(A_1 A_2 A_3 A_4\right)^4=e^{i \pi\left(\frac{1}{2}+\frac{1}{4}+\frac{1}{8}+\frac{1}{16}\right)^4}\)…