1. ## complex numbers help please

Draw the points A : i
and the point B: (1/(20.5)) + (1/(20.5))i on a argand digram and hence find the argument of A+B i drew it but i am clueless

2. ## Re: complex numbers help please

Originally Posted by righteous818
Draw the points A : i
and the point B: (1/(20.5)) + (1/(20.5))i on a argand digram and hence find the argument of A+B i drew it but i am clueless
$\displaystyle \arg (i) = \frac{\pi }{2}\;\& \;\arg \left( {\frac{{\sqrt 2 }}{2} + \frac{{\sqrt 2 }}{2}i} \right) = \frac{\pi }{4}$

The $\displaystyle \arg(A+B)=\arctan\left(\frac{\sqrt2+2}{\sqrt2} \right)$

3. ## Re: complex numbers help please

they the mark scheme has 3pi/8 and specifically gave no marks for using that forumla and approximating the answer to 3pi/8, they said not to use that formula, they stressed to use the argand diagram to find it, any suggestions how, i did this first but then realised that they did not accept this method..please help

i forgot to mention they want the argument exactly in terms of pi, and have no marks for find A+B and finidnging the argument from that

4. ## Re: complex numbers help please

Note that OACB is a parallelogram, and thus OC is the bisector of ∠AOB.

5. ## Re: complex numbers help please

what is the program you use to plot the function an show it is a paralleogram

6. ## Re: complex numbers help please

To draw the diagram I used TikZ, and to prove that it is a parallelogram I used my wetware.