Medium MCQ +4 / -1 PYQ · JEE Mains 2022

Let z1 and z2 be two complex numbers such that ${\overline z _1} = i{\overline z _2}$ and $\arg \left( {{{{z_1}} \over {{{\overline z }_2}}}} \right) = \pi$. Then :

  1. A $\arg {z_2} = {\pi \over 4}$
  2. B $\arg {z_2} = - {{3\pi } \over 4}$
  3. C $\arg {z_1} = {\pi \over 4}$ Correct answer
  4. D $\arg {z_1} = - {{3\pi } \over 4}$

Solution

<p>$\because$ ${{{z_1}} \over {{z_2}}} = - i \Rightarrow {z_1} = - i{z_2}$</p> <p>$\Rightarrow \arg ({z_1}) = - {\pi \over 2} + \arg ({z_2})$ ..... (i)</p> <p>Also $\arg ({z_1}) - \arg ({\overline z _2}) = \pi$</p> <p>$\Rightarrow \arg ({z_1}) + \arg ({z_2}) = \pi$ ..... (ii)</p> <p>From (i) and (ii), we get</p> <p>$\arg ({z_1}) = {\pi \over 4}$ and $\arg ({z_2}) = {{3\pi } \over 4}$</p>

About this question

Subject: Mathematics · Chapter: Complex Numbers and Quadratic Equations · Topic: Modulus and Argument

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