1. ## Evaluation of Cos(2/3+i2)

Ok basically I need to:

Express $\displaystyle cos(\frac{2}{3}+i2)$ in the form $\displaystyle x+iy$

I've done the following:

$\displaystyle cos(\frac{2}{3}+i2) = cos(\frac{2}{3})cosh(2)-isin(\frac{2}{3})sinh2$
$\displaystyle =0.7859 X 3.7622 - i(0.6184 X 3.6269)$
$\displaystyle = 2.9567-i(2.249)$

Is this the correct answer? My professor has $\displaystyle 0.759567 + i(2.8503)$ as the answer?

2. ## Re: Evaluation of Cos(2/3+i2)

Originally Posted by Umair
Ok basically I need to:

Express $\displaystyle cos(\frac{2}{3}+i2)$ in the form $\displaystyle x+iy$

I've done the following:

$\displaystyle cos(\frac{2}{3}+i2) = cos(\frac{2}{3})cosh(2)-isin(\frac{2}{3})sinh2$
$\displaystyle =0.7859 X 3.7622 - i(0.6184 X 3.6269)$
$\displaystyle = 2.9567-i(2.249)$

Is this the correct answer? My professor has $\displaystyle 0.759567 + i(2.8503)$ as the answer?
Cos&#91;&#40;2&#47;3&#41; &#43; 2i&#93; - Wolfram|Alpha

3. ## Re: Evaluation of Cos(2/3+i2)

^l0lwut? urm thx...I think i'm right then lol

4. ## Re: Evaluation of Cos(2/3+i2)

According to wolphram alpha it looks you're right.