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

Let a circle C in complex plane pass through the points ${z_1} = 3 + 4i$, ${z_2} = 4 + 3i$ and ${z_3} = 5i$. If $z( \ne {z_1})$ is a point on C such that the line through z and z1 is perpendicular to the line through z2 and z3, then $arg(z)$ is equal to :

  1. A ${\tan ^{ - 1}}\left( {{2 \over {\sqrt 5 }}} \right) - \pi$
  2. B ${\tan ^{ - 1}}\left( {{{24} \over 7}} \right) - \pi$ Correct answer
  3. C ${\tan ^{ - 1}}\left( 3 \right) - \pi$
  4. D ${\tan ^{ - 1}}\left( {{3 \over 4}} \right) - \pi$

Solution

<p>${z_1} = 3 + 4i$, ${z_2} = 4 + 3i$ and ${z_3} = 5i$</p> <p>Clearly, $C \equiv {x^2} + {y^2} = 25$</p> <p>Let $z(x,y)$</p> <p>$$ \Rightarrow \left( {{{y - 4} \over {x - 3}}} \right)\left( {{2 \over { - 4}}} \right) = - 1$$</p> <p>$\Rightarrow y = 2x - 2 \equiv L$</p> <p>$\therefore$ z is intersection of C & L</p> <p>$\Rightarrow z \equiv \left( {{{ - 7} \over 5},{{ - 24} \over 5}} \right)$</p> <p>$\therefore$ $Arg(z) = - \pi + {\tan ^{ - 1}}\left( {{{24} \over 7}} \right)$</p>

About this question

Subject: Mathematics · Chapter: Complex Numbers and Quadratic Equations · Topic: Complex Numbers and Argand Plane

This question is part of PrepWiser's free JEE Main question bank. 223 more solved questions on Complex Numbers and Quadratic Equations are available — start with the harder ones if your accuracy is >70%.

Drill 25 more like these. Every day. Free.

PrepWiser turns these solved questions into a daily practice loop. Chapter-wise drills, full mocks, AI doubt chat. No auto-renew.

Start free →