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Select the correct answer from the given alternatives: If -1+3i = reiθ , then θ = .................

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Question

Select the correct answer from the given alternatives:

If `-1 + sqrt(3)"i"` = re , then θ = ................. 

Options

  • `-(2pi)/3`

  • `pi/3`

  • `-pi/3`

  • `(2pi)/3`

MCQ
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Solution

`(2pi)/3`

Explanation;

re = `-1 + "i"sqrt(3)`

= `2((-1)/2 + "i"sqrt(3)/2)    ...[("a" = (-1)/2),("b" = sqrt(3)/2)]`

= `2[cos(pi - pi/3) + "i"sin (pi - pi/3)]`

= `2(cos  (2pi)/3 + "i"sin  (2pi)/3)`

∴ θ = `(2pi)/3`.

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Chapter 1: Complex Numbers - Miscellaneous Exercise 1.1 [Page 21]

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Balbharati Mathematics and Statistics 2 (Arts and Science) [English] Standard 11 Maharashtra State Board
Chapter 1 Complex Numbers
Miscellaneous Exercise 1.1 | Q I. (9) | Page 21

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