Convert (1-i)(2+2i) to trig notation and then multiply

I get:

Book answer is:

My first part is wrong, why???

Also I have a general question other than this current problem. Why are the angles always the same in each point?

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- July 20th 2012, 08:24 AMGreymalkinImaginary to trig notation
Convert (1-i)(2+2i) to trig notation and then multiply

__I get:__

__Book answer is:__

My first part is wrong, why???

Also I have a general question other than this current problem. Why are the angles always the same in each point? - July 20th 2012, 08:38 AMa tutorRe: Imaginary to trig notation
You're nearly right. The answer is 4i.

- July 20th 2012, 08:39 AMPlatoRe: Imaginary to trig notation
- July 20th 2012, 08:48 AMGreymalkinRe: Imaginary to trig notation
- July 20th 2012, 08:53 AMa tutorRe: Imaginary to trig notation
- July 20th 2012, 08:58 AMGreymalkinRe: Imaginary to trig notation
It also appears that my brain isnt into math on fridays :)

- July 20th 2012, 09:09 AMILikeSerenaRe: Imaginary to trig notation
Hmm, I do not know what you edited, but the answer should be 4i.

You seem to have deduced an angle of 315 degrees for (1+i).

But that angle should be 45 degrees.

It seems you had that before, but then you also got 4, which is still wrong - it really should be 4i.

Note that . - July 20th 2012, 09:17 AMGreymalkinRe: Imaginary to trig notation