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AP EAMCET · Maths · Complex Number

(sinθ-icosθ)3 is equal to

  1. A i3(cos3θ+isin3θ)
  2. B cos3θ+isin3θ
  3. C sin3θicos3θ
  4. D (i)3(cos3θ+isin3θ)
Verified Solution

Answer & Solution

Correct Answer

(D) (i)3(cos3θ+isin3θ)

Step-by-step Solution

Detailed explanation

Given (sinθ-icosθ)3 Multiplying and dividing by i, we get 1i·i·sinθ-icosθ3 =-iisinθ+cosθ3 (Because 1i=-i) =-i3cosθ+isinθ3 According to De Moivre's Theorem, For n be any rational number,…