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Let   \frac{z_{1}}{z_{2}}= 3-4i  and  z_{2}= 12+5i  then \left |z_{1} \right |  equals

  • Option 1)

    \frac{13}{5}

  • Option 2)

    \frac{5}{13}

  • Option 3)

    \frac{1}{65}

  • Option 4)

    65

 

Answers (1)

best_answer

\because \left | \frac{z_{1}}{z_{2}} \right |=\frac{\left |z_{1} \right |}{\left |z_{2} \right |}\Rightarrow \left | z_{1} \right |=\left | \frac{z_{1}}{z_{2}} \right |\cdot \left | z_{2} \right |

From given, we have 

\left | \frac{z_{1}}{z_{2}} \right |=\sqrt{9+16}=5  and  \left | z_{2} \right |=\sqrt{144+25}=13

\therefore \left |z_{1} \right |=5\times 13=65

\therefore Option (D)

 

Property of Modulus of z(Complex Number) -

\left |\frac{z_{1}}{z_{2}} \right |=\frac{\left |z_{1} \right |}{\left |z_{2} \right |}

- wherein

|.| denotes modulus of complex number

 

 


Option 1)

\frac{13}{5}

This is incorrect

Option 2)

\frac{5}{13}

This is incorrect

Option 3)

\frac{1}{65}

This is incorrect

Option 4)

65

This is correct

Posted by

prateek

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