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Question: Answered & Verified by Expert
Real part of (cos4+isin4+1)2020 is_______
MathematicsComplex NumberAP EAMCETAP EAMCET 2021 (19 Aug Shift 1)
Options:
  • A 22020cos20202cos2020
  • B 22020cos20202cos4040
  • C 21020cos20202cos4040
  • D 22020cos20201cos2020
Solution:
2504 Upvotes Verified Answer
The correct answer is: 22020cos20202cos4040

Given, (cos4+isin4+1)2020

Now using, 1+cos2A=2cos2A and sin2A=2sinAcosA, we get

2cos22+2isin2cos22020

2cos2cos2+isin22020

Now, By using De Moivre's Theorem, we get

22020cos20202cos2×2020+isin2×2020

22020cos20202cos4040+isin4040

Hence, the Real part is 22020cos20202cos4040

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