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Select the correct answer from the given alternatives: The modulus and argument of (1+i3)8 are respectively

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Question

Select the correct answer from the given alternatives:

The modulus and argument of `(1 + "i"sqrt(3))^8` are respectively

Options

  • 2 and `(2pi)/3`

  • 256 and `(8pi)/3`

  • 256 and `(2pi)/3`

  • 64 and `(4pi)/3`

MCQ
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Solution

256 and `(2pi)/3`

Explanation:

Let z = `(1 + "i"sqrt(3))^8` = [r (cos θ + i sin θ)]8 

r cos θ = 1, r sin θ  = `sqrt(3)`,

r = `sqrt(1 + 3)`

= 2

∴ cos θ = `1/2`, sin θ  = `sqrt(3)/2`

∴ arg z = `pi/3`

z = `[2(cos  pi/3 + "i"sin  pi/3)]^8`

= `2^8 (cos  (8pi)/3 + "i" sin  (8pi)/3)`

= `256[cos(2pi + (2pi)/3) + "i"sin(2pi + (2pi)/3)]`

= `256[cos  (2pi)/3 + "i"sin  (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. (7) | Page 21

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