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The point represented by the complex number 2 – i is rotated about origin through an angle π2 in the clockwise direction, the new position of point is ______.

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Question

The point represented by the complex number 2 – i is rotated about origin through an angle `pi/2` in the clockwise direction, the new position of point is ______.

Options

  • 1 + 2i

  • –1 – 2i

  • 2 + i

  • –1 + 2i

MCQ
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Solution

The point represented by the complex number 2 – i is rotated about origin through an angle `pi/2` in the clockwise direction, the new position of point is –1 – 2i.

Explanation:

Given that: z = 2 – i

If z rotated through an angle of `pi/2` about the origin in clockwise direction.

Then the new position = `z.e^(-(pi/2))`

= `(2 - i) e^(-(pi/2))`

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

= (2 – i)(0 – i)

= –1 – 2i

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Chapter 5: Complex Numbers and Quadratic Equations - Exercise [Page 96]

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NCERT Exemplar Mathematics [English] Class 11
Chapter 5 Complex Numbers and Quadratic Equations
Exercise | Q 42 | Page 96

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