Write the complex number in rectangular form. 3cis52degrees ( round to 3 decimal places)

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- May 6th 2013, 09:21 PMboltage619Write the complex number in rectangular form.
Write the complex number in rectangular form. 3cis52degrees ( round to 3 decimal places)

- May 6th 2013, 09:35 PMMarkFLRe: Write the complex number in rectangular form.
What does $\displaystyle \text{cis}(\theta)$ mean? What I mean, is use the definition, write it out, then use your calculator to evaluate the trig. functions.

- May 6th 2013, 09:40 PMboltage619Re: Write the complex number in rectangular form.
Cis = Cos * i sin

- May 6th 2013, 09:45 PMMarkFLRe: Write the complex number in rectangular form.
No, $\displaystyle \text{cis}(\theta)\equiv\cos(\theta)+i\sin(\theta)$.

So how would you expand $\displaystyle 3\,\text{cis}\left(52^{\circ} \right)$ ? - May 6th 2013, 09:50 PMboltage619Re: Write the complex number in rectangular form.
Wouldn't it be 3*cos52 + 3 * i sin52?

- May 6th 2013, 09:56 PMMarkFLRe: Write the complex number in rectangular form.
Yes, that's right, now just use your calculator to approximate the rectangular components. Rectangular form is:

$\displaystyle a+bi$ where $\displaystyle a,b\in\mathbb{R}$ (i.e. $\displaystyle a$ and $\displaystyle b$ are real.)

Here we have:

$\displaystyle a=3\cos\left(52^{\circ} \right)$

$\displaystyle b=3\sin\left(52^{\circ} \right)$ - May 6th 2013, 10:00 PMboltage619Re: Write the complex number in rectangular form.
I got 1.847+2.364i as my answer, is that right?

- May 6th 2013, 10:09 PMMarkFLRe: Write the complex number in rectangular form.
Yes, that's correct! Good work! :D

- May 6th 2013, 10:11 PMboltage619Re: Write the complex number in rectangular form.
Thank you! :D