If $z_1,z_2$ satisfy $z+bar{z}=2|z-1|$, $arg(z_1-z_2)=dfrac{pi}{4}$, then find $Im(z_1+z_2)$












3












$begingroup$



If $z_1$ and $z_2$ both satisfy $z+bar{z}=2|z-1|$, $arg(z_1-z_2)=dfrac{pi}{4}$, then find $Im(z_1+z_2)$




My Attempt
$$
z_1+bar{z}_1=2|z_1-1|quad&quad z_2+bar{z}_2=2|z_2-1|quad&quad arg(z_1-z_2)=dfrac{pi}{4}\
z_1-z_2=frac{|z_1-z_2|}{sqrt{2}}Big(1+iBig)\
Re(z_1+z_2)=frac{z_1+z_2+bar{z}_1+bar{z}_2}{2}=|z_1-1|+|z_2-1|\
Im(z_1+z_2)=frac{z_1+z_2-bar{z}_1-bar{z}_2}{2i}\
Re(z_1-z_2)=frac{z_1-z_2+bar{z}_1-bar{z}_2}{2}=frac{|z_1-z_2|}{sqrt{2}}={|z_1-1|-|z_2-1|}\
Im(z_1-z_2)=frac{z_1-z_2-bar{z}_1+bar{z}_2}{2i}=frac{|z_1-z_2|}{sqrt{2}}
$$

My reference gives the solution $2$, but how do I find the solution without actually representing $z=a+ib$ ?










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$endgroup$

















    3












    $begingroup$



    If $z_1$ and $z_2$ both satisfy $z+bar{z}=2|z-1|$, $arg(z_1-z_2)=dfrac{pi}{4}$, then find $Im(z_1+z_2)$




    My Attempt
    $$
    z_1+bar{z}_1=2|z_1-1|quad&quad z_2+bar{z}_2=2|z_2-1|quad&quad arg(z_1-z_2)=dfrac{pi}{4}\
    z_1-z_2=frac{|z_1-z_2|}{sqrt{2}}Big(1+iBig)\
    Re(z_1+z_2)=frac{z_1+z_2+bar{z}_1+bar{z}_2}{2}=|z_1-1|+|z_2-1|\
    Im(z_1+z_2)=frac{z_1+z_2-bar{z}_1-bar{z}_2}{2i}\
    Re(z_1-z_2)=frac{z_1-z_2+bar{z}_1-bar{z}_2}{2}=frac{|z_1-z_2|}{sqrt{2}}={|z_1-1|-|z_2-1|}\
    Im(z_1-z_2)=frac{z_1-z_2-bar{z}_1+bar{z}_2}{2i}=frac{|z_1-z_2|}{sqrt{2}}
    $$

    My reference gives the solution $2$, but how do I find the solution without actually representing $z=a+ib$ ?










    share|cite|improve this question











    $endgroup$















      3












      3








      3


      1



      $begingroup$



      If $z_1$ and $z_2$ both satisfy $z+bar{z}=2|z-1|$, $arg(z_1-z_2)=dfrac{pi}{4}$, then find $Im(z_1+z_2)$




      My Attempt
      $$
      z_1+bar{z}_1=2|z_1-1|quad&quad z_2+bar{z}_2=2|z_2-1|quad&quad arg(z_1-z_2)=dfrac{pi}{4}\
      z_1-z_2=frac{|z_1-z_2|}{sqrt{2}}Big(1+iBig)\
      Re(z_1+z_2)=frac{z_1+z_2+bar{z}_1+bar{z}_2}{2}=|z_1-1|+|z_2-1|\
      Im(z_1+z_2)=frac{z_1+z_2-bar{z}_1-bar{z}_2}{2i}\
      Re(z_1-z_2)=frac{z_1-z_2+bar{z}_1-bar{z}_2}{2}=frac{|z_1-z_2|}{sqrt{2}}={|z_1-1|-|z_2-1|}\
      Im(z_1-z_2)=frac{z_1-z_2-bar{z}_1+bar{z}_2}{2i}=frac{|z_1-z_2|}{sqrt{2}}
      $$

      My reference gives the solution $2$, but how do I find the solution without actually representing $z=a+ib$ ?










      share|cite|improve this question











      $endgroup$





      If $z_1$ and $z_2$ both satisfy $z+bar{z}=2|z-1|$, $arg(z_1-z_2)=dfrac{pi}{4}$, then find $Im(z_1+z_2)$




      My Attempt
      $$
      z_1+bar{z}_1=2|z_1-1|quad&quad z_2+bar{z}_2=2|z_2-1|quad&quad arg(z_1-z_2)=dfrac{pi}{4}\
      z_1-z_2=frac{|z_1-z_2|}{sqrt{2}}Big(1+iBig)\
      Re(z_1+z_2)=frac{z_1+z_2+bar{z}_1+bar{z}_2}{2}=|z_1-1|+|z_2-1|\
      Im(z_1+z_2)=frac{z_1+z_2-bar{z}_1-bar{z}_2}{2i}\
      Re(z_1-z_2)=frac{z_1-z_2+bar{z}_1-bar{z}_2}{2}=frac{|z_1-z_2|}{sqrt{2}}={|z_1-1|-|z_2-1|}\
      Im(z_1-z_2)=frac{z_1-z_2-bar{z}_1+bar{z}_2}{2i}=frac{|z_1-z_2|}{sqrt{2}}
      $$

      My reference gives the solution $2$, but how do I find the solution without actually representing $z=a+ib$ ?







      complex-numbers






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      edited Jan 9 at 6:56







      ss1729

















      asked Jan 8 at 10:07









      ss1729ss1729

      2,07811124




      2,07811124






















          2 Answers
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          2












          $begingroup$

          It's easy if you consider



          $z_1=a_1+ib_1$ , $z_2=a_2+ib_2$



          $bar{z_1}=a_1-ib_1$ , $bar{z_2}=a_2-ib_2$



          Given $z+bar{z}=2|z-1|$



          Since, $z_1$ and $z_2$ both satisfy, $z+bar{z}=2|z-1|$, we can say that $$z_1+bar{z_1}=2|z_1-1|$$ and $$z_2+bar{z_2}=2|z_2-1|$$



          Firstly, $$z_1+bar{z_1}=2|z_1-1|$$
          $$a_1+ib_1+a_1-ib_1=2|(a_1-1)+ib_1|$$
          After solving we get, $$b_1^2=2a_1-1tag1$$
          Similarly, we get $$b_1^2=2a_2-1tag3$$



          Now, $$arg(z_1-z_2)=dfrac{pi}{4}$$
          $$arg(a_1+ib_1-a_2-ib_2)=dfrac{pi}{4}$$
          $$dfrac{b_1-b_2}{a_1-a_2}=tandfrac{pi}{4}$$
          $$dfrac{b_1-b_2}{a_1-a_2}=1$$
          $$b_1-b_2=a_1-a_2tag3$$
          Now use the equations $(1),(2)$ and $(3)$ to get the final answer.






          share|cite|improve this answer









          $endgroup$





















            2












            $begingroup$

            Without representing $z=a+bi$.
            begin{align}
            z+bar z&=2|z-1|\
            (z+bar z)^2&=4|z-1|^2=4(z-1)(bar z-1)\
            z^2+2zbar z+bar z^2&=4(zbar z-z-bar z+1)\
            z^2-2zbar z+bar z^2&=4-4(z+bar z)\
            (z-bar z)^2&=4-4(z+bar z)tag{1}
            end{align}

            Now take (1) for $z_2$ minus (1) for $z_1$ and use
            $$
            z_1-z_2=frac{|z_1-z_2|}{sqrt{2}}(1+i)tag{2}
            $$

            to get
            begin{align}
            (z_2-bar z_2)^2-(z_1-bar z_1)^2&=4(z_1+bar z_1-z_2-bar z_2)\
            (underbrace{z_2-bar z_2-z_1+bar z_1}_{-sqrt2i|z_1-z_2|})(underbrace{z_2-bar z_2+z_1-bar z_1}_{2ioperatorname{Im}(z_1+z_2)})&=4(underbrace{z_1+bar z_1-z_2-bar z_2}_{sqrt2|z_1-z_2|})\
            |z_1-z_2|(operatorname{Im}(z_1+z_2)-2)&=0.
            end{align}






            share|cite|improve this answer









            $endgroup$














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              2 Answers
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              2 Answers
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              2












              $begingroup$

              It's easy if you consider



              $z_1=a_1+ib_1$ , $z_2=a_2+ib_2$



              $bar{z_1}=a_1-ib_1$ , $bar{z_2}=a_2-ib_2$



              Given $z+bar{z}=2|z-1|$



              Since, $z_1$ and $z_2$ both satisfy, $z+bar{z}=2|z-1|$, we can say that $$z_1+bar{z_1}=2|z_1-1|$$ and $$z_2+bar{z_2}=2|z_2-1|$$



              Firstly, $$z_1+bar{z_1}=2|z_1-1|$$
              $$a_1+ib_1+a_1-ib_1=2|(a_1-1)+ib_1|$$
              After solving we get, $$b_1^2=2a_1-1tag1$$
              Similarly, we get $$b_1^2=2a_2-1tag3$$



              Now, $$arg(z_1-z_2)=dfrac{pi}{4}$$
              $$arg(a_1+ib_1-a_2-ib_2)=dfrac{pi}{4}$$
              $$dfrac{b_1-b_2}{a_1-a_2}=tandfrac{pi}{4}$$
              $$dfrac{b_1-b_2}{a_1-a_2}=1$$
              $$b_1-b_2=a_1-a_2tag3$$
              Now use the equations $(1),(2)$ and $(3)$ to get the final answer.






              share|cite|improve this answer









              $endgroup$


















                2












                $begingroup$

                It's easy if you consider



                $z_1=a_1+ib_1$ , $z_2=a_2+ib_2$



                $bar{z_1}=a_1-ib_1$ , $bar{z_2}=a_2-ib_2$



                Given $z+bar{z}=2|z-1|$



                Since, $z_1$ and $z_2$ both satisfy, $z+bar{z}=2|z-1|$, we can say that $$z_1+bar{z_1}=2|z_1-1|$$ and $$z_2+bar{z_2}=2|z_2-1|$$



                Firstly, $$z_1+bar{z_1}=2|z_1-1|$$
                $$a_1+ib_1+a_1-ib_1=2|(a_1-1)+ib_1|$$
                After solving we get, $$b_1^2=2a_1-1tag1$$
                Similarly, we get $$b_1^2=2a_2-1tag3$$



                Now, $$arg(z_1-z_2)=dfrac{pi}{4}$$
                $$arg(a_1+ib_1-a_2-ib_2)=dfrac{pi}{4}$$
                $$dfrac{b_1-b_2}{a_1-a_2}=tandfrac{pi}{4}$$
                $$dfrac{b_1-b_2}{a_1-a_2}=1$$
                $$b_1-b_2=a_1-a_2tag3$$
                Now use the equations $(1),(2)$ and $(3)$ to get the final answer.






                share|cite|improve this answer









                $endgroup$
















                  2












                  2








                  2





                  $begingroup$

                  It's easy if you consider



                  $z_1=a_1+ib_1$ , $z_2=a_2+ib_2$



                  $bar{z_1}=a_1-ib_1$ , $bar{z_2}=a_2-ib_2$



                  Given $z+bar{z}=2|z-1|$



                  Since, $z_1$ and $z_2$ both satisfy, $z+bar{z}=2|z-1|$, we can say that $$z_1+bar{z_1}=2|z_1-1|$$ and $$z_2+bar{z_2}=2|z_2-1|$$



                  Firstly, $$z_1+bar{z_1}=2|z_1-1|$$
                  $$a_1+ib_1+a_1-ib_1=2|(a_1-1)+ib_1|$$
                  After solving we get, $$b_1^2=2a_1-1tag1$$
                  Similarly, we get $$b_1^2=2a_2-1tag3$$



                  Now, $$arg(z_1-z_2)=dfrac{pi}{4}$$
                  $$arg(a_1+ib_1-a_2-ib_2)=dfrac{pi}{4}$$
                  $$dfrac{b_1-b_2}{a_1-a_2}=tandfrac{pi}{4}$$
                  $$dfrac{b_1-b_2}{a_1-a_2}=1$$
                  $$b_1-b_2=a_1-a_2tag3$$
                  Now use the equations $(1),(2)$ and $(3)$ to get the final answer.






                  share|cite|improve this answer









                  $endgroup$



                  It's easy if you consider



                  $z_1=a_1+ib_1$ , $z_2=a_2+ib_2$



                  $bar{z_1}=a_1-ib_1$ , $bar{z_2}=a_2-ib_2$



                  Given $z+bar{z}=2|z-1|$



                  Since, $z_1$ and $z_2$ both satisfy, $z+bar{z}=2|z-1|$, we can say that $$z_1+bar{z_1}=2|z_1-1|$$ and $$z_2+bar{z_2}=2|z_2-1|$$



                  Firstly, $$z_1+bar{z_1}=2|z_1-1|$$
                  $$a_1+ib_1+a_1-ib_1=2|(a_1-1)+ib_1|$$
                  After solving we get, $$b_1^2=2a_1-1tag1$$
                  Similarly, we get $$b_1^2=2a_2-1tag3$$



                  Now, $$arg(z_1-z_2)=dfrac{pi}{4}$$
                  $$arg(a_1+ib_1-a_2-ib_2)=dfrac{pi}{4}$$
                  $$dfrac{b_1-b_2}{a_1-a_2}=tandfrac{pi}{4}$$
                  $$dfrac{b_1-b_2}{a_1-a_2}=1$$
                  $$b_1-b_2=a_1-a_2tag3$$
                  Now use the equations $(1),(2)$ and $(3)$ to get the final answer.







                  share|cite|improve this answer












                  share|cite|improve this answer



                  share|cite|improve this answer










                  answered Jan 8 at 10:33









                  Key FlexKey Flex

                  8,56171233




                  8,56171233























                      2












                      $begingroup$

                      Without representing $z=a+bi$.
                      begin{align}
                      z+bar z&=2|z-1|\
                      (z+bar z)^2&=4|z-1|^2=4(z-1)(bar z-1)\
                      z^2+2zbar z+bar z^2&=4(zbar z-z-bar z+1)\
                      z^2-2zbar z+bar z^2&=4-4(z+bar z)\
                      (z-bar z)^2&=4-4(z+bar z)tag{1}
                      end{align}

                      Now take (1) for $z_2$ minus (1) for $z_1$ and use
                      $$
                      z_1-z_2=frac{|z_1-z_2|}{sqrt{2}}(1+i)tag{2}
                      $$

                      to get
                      begin{align}
                      (z_2-bar z_2)^2-(z_1-bar z_1)^2&=4(z_1+bar z_1-z_2-bar z_2)\
                      (underbrace{z_2-bar z_2-z_1+bar z_1}_{-sqrt2i|z_1-z_2|})(underbrace{z_2-bar z_2+z_1-bar z_1}_{2ioperatorname{Im}(z_1+z_2)})&=4(underbrace{z_1+bar z_1-z_2-bar z_2}_{sqrt2|z_1-z_2|})\
                      |z_1-z_2|(operatorname{Im}(z_1+z_2)-2)&=0.
                      end{align}






                      share|cite|improve this answer









                      $endgroup$


















                        2












                        $begingroup$

                        Without representing $z=a+bi$.
                        begin{align}
                        z+bar z&=2|z-1|\
                        (z+bar z)^2&=4|z-1|^2=4(z-1)(bar z-1)\
                        z^2+2zbar z+bar z^2&=4(zbar z-z-bar z+1)\
                        z^2-2zbar z+bar z^2&=4-4(z+bar z)\
                        (z-bar z)^2&=4-4(z+bar z)tag{1}
                        end{align}

                        Now take (1) for $z_2$ minus (1) for $z_1$ and use
                        $$
                        z_1-z_2=frac{|z_1-z_2|}{sqrt{2}}(1+i)tag{2}
                        $$

                        to get
                        begin{align}
                        (z_2-bar z_2)^2-(z_1-bar z_1)^2&=4(z_1+bar z_1-z_2-bar z_2)\
                        (underbrace{z_2-bar z_2-z_1+bar z_1}_{-sqrt2i|z_1-z_2|})(underbrace{z_2-bar z_2+z_1-bar z_1}_{2ioperatorname{Im}(z_1+z_2)})&=4(underbrace{z_1+bar z_1-z_2-bar z_2}_{sqrt2|z_1-z_2|})\
                        |z_1-z_2|(operatorname{Im}(z_1+z_2)-2)&=0.
                        end{align}






                        share|cite|improve this answer









                        $endgroup$
















                          2












                          2








                          2





                          $begingroup$

                          Without representing $z=a+bi$.
                          begin{align}
                          z+bar z&=2|z-1|\
                          (z+bar z)^2&=4|z-1|^2=4(z-1)(bar z-1)\
                          z^2+2zbar z+bar z^2&=4(zbar z-z-bar z+1)\
                          z^2-2zbar z+bar z^2&=4-4(z+bar z)\
                          (z-bar z)^2&=4-4(z+bar z)tag{1}
                          end{align}

                          Now take (1) for $z_2$ minus (1) for $z_1$ and use
                          $$
                          z_1-z_2=frac{|z_1-z_2|}{sqrt{2}}(1+i)tag{2}
                          $$

                          to get
                          begin{align}
                          (z_2-bar z_2)^2-(z_1-bar z_1)^2&=4(z_1+bar z_1-z_2-bar z_2)\
                          (underbrace{z_2-bar z_2-z_1+bar z_1}_{-sqrt2i|z_1-z_2|})(underbrace{z_2-bar z_2+z_1-bar z_1}_{2ioperatorname{Im}(z_1+z_2)})&=4(underbrace{z_1+bar z_1-z_2-bar z_2}_{sqrt2|z_1-z_2|})\
                          |z_1-z_2|(operatorname{Im}(z_1+z_2)-2)&=0.
                          end{align}






                          share|cite|improve this answer









                          $endgroup$



                          Without representing $z=a+bi$.
                          begin{align}
                          z+bar z&=2|z-1|\
                          (z+bar z)^2&=4|z-1|^2=4(z-1)(bar z-1)\
                          z^2+2zbar z+bar z^2&=4(zbar z-z-bar z+1)\
                          z^2-2zbar z+bar z^2&=4-4(z+bar z)\
                          (z-bar z)^2&=4-4(z+bar z)tag{1}
                          end{align}

                          Now take (1) for $z_2$ minus (1) for $z_1$ and use
                          $$
                          z_1-z_2=frac{|z_1-z_2|}{sqrt{2}}(1+i)tag{2}
                          $$

                          to get
                          begin{align}
                          (z_2-bar z_2)^2-(z_1-bar z_1)^2&=4(z_1+bar z_1-z_2-bar z_2)\
                          (underbrace{z_2-bar z_2-z_1+bar z_1}_{-sqrt2i|z_1-z_2|})(underbrace{z_2-bar z_2+z_1-bar z_1}_{2ioperatorname{Im}(z_1+z_2)})&=4(underbrace{z_1+bar z_1-z_2-bar z_2}_{sqrt2|z_1-z_2|})\
                          |z_1-z_2|(operatorname{Im}(z_1+z_2)-2)&=0.
                          end{align}







                          share|cite|improve this answer












                          share|cite|improve this answer



                          share|cite|improve this answer










                          answered Jan 8 at 12:48









                          A.Γ.A.Γ.

                          22.9k32656




                          22.9k32656






























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