BCECE Engineering BCECE Engineering Solved Paper-2014

  • question_answer
    If P, Q, R and S are represented by the complex numbers  \[4+i,\] \[1+6i,\] \[-4+3i,\] \[-1-2i\] respectively, then PQRS is a     

    A) rectangle            

    B) square

    C) rhombus             

    D) parallelogram

    Correct Answer: B

    Solution :

    Given complex number are \[P(4+i),Q(1+6i),\] \[R(-4+3i)\]and \[S(-1-2i).\] Now , \[|PQ|=\sqrt{{{(4-1)}^{2}}+{{(1-6)}^{2}}}\] \[=\sqrt{9+25}=\sqrt{34}\] \[|QR|=\sqrt{{{(1+4)}^{2}}+{{(6-3)}^{2}}}\] \[=\sqrt{25+9}=\sqrt{34}\]                 \[|RS|=\sqrt{{{(-4+1)}^{2}}+{{(3+2)}^{2}}}\] \[=\sqrt{9+25}=\sqrt{34}\]                 and        \[|SP|=\sqrt{{{(1-1-4)}^{2}}+{{(-2-1)}^{2}}}\]                                 \[=\sqrt{25+9}=\sqrt{34}\]                 \[\therefore \]  \[|PQ|=|QR|=|RS|=|SP|\]                 Now,     \[|PR|=\sqrt{{{(4+4)}^{2}}+{{(1-3)}^{3}}}\]                                 \[=\sqrt{64+4}=\sqrt{68}\]                 and        \[|QS|=\sqrt{{{(1+1)}^{2}}+{{(6+2)}^{2}}}\]                                 \[\sqrt{4+64}=\sqrt{68}\]                 \[\therefore \]  \[|PR|=|QS|\]                 Hence, it is a square.


You need to login to perform this action.
You will be redirected in 3 sec spinner