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Question 230023
JEE Mathematics · Medium

Complex Numbers: Mixed MCQ

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MixedMediumQuestion 230023

Question

If z = cos θ + i sin θ, then z + 1/z equals:
  1. A
    2cos θ
    Correct
  2. B
    2i sin θ
  3. C
    2
  4. D
    cos 2θ + i sin 2θ

Correct answer

2cos θ

Explanation

1/z = cos(−θ) + i sin(−θ) = cos θ − i sin θ. So z + 1/z = 2cos θ. (This is Euler's formula result.)

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