Hi I really do not know how to do this.

Write sin2a-cos2ai in modulus argument form

I was thinking of changing sin2a to cos(pi/2 - 2a)..

Will really appreciate the help! Thanks,

J.

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- Nov 16th 2012, 10:11 PMTutuQuestion involving complex numbers
Hi I really do not know how to do this.

Write sin2a-cos2ai in modulus argument form

I was thinking of changing sin2a to cos(pi/2 - 2a)..

Will really appreciate the help! Thanks,

J. - Nov 16th 2012, 10:22 PMchiroRe: Question involving complex numbers
Hey Tutu.

What is modulus argument form? Is that in terms of re^(i*theta) where r = 1? - Nov 16th 2012, 10:26 PMProve ItRe: Question involving complex numbers
Notice this is in the Cartesian Form $\displaystyle \displaystyle \begin{align*} x + y\,i \end{align*}$ with $\displaystyle \displaystyle \begin{align*} x = \sin{(2a)} \end{align*}$ and $\displaystyle \displaystyle \begin{align*} y = \cos{(2a)} \end{align*}$. You need to write it in the modulus-argument form $\displaystyle \displaystyle \begin{align*} r\, e^{i\,\theta} \end{align*}$ with $\displaystyle \displaystyle \begin{align*} r = \sqrt{x^2 + y^2} \end{align*}$ and $\displaystyle \displaystyle \begin{align*} \theta = \arctan{\left( \frac{y}{x} \right)} \end{align*}$.

- Nov 16th 2012, 10:42 PMTutuRe: Question involving complex numbers
From what I've learnt, modulus-argument form is the polar form where it is rcis(thetha) where r is positive.

re^i(thetha) is exponential form for me.

The answer of this question is in cis form, not exponential form. - Nov 16th 2012, 11:14 PMProve ItRe: Question involving complex numbers
- Nov 16th 2012, 11:56 PMTutuRe: Question involving complex numbers
Sorry, I do not understand..

Can you show me how you would do it? - Nov 17th 2012, 12:14 AMProve ItRe: Question involving complex numbers
You already have x and y. Evaluate $\displaystyle \displaystyle \begin{align*} r = \sqrt{x^2 + y^2} \end{align*}$ and $\displaystyle \displaystyle \begin{align*} \theta = \arctan{\left( \frac{y}{x} \right)} \end{align*}$.