Thread: Imaginary 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?

You're nearly right. The answer is 4i.

Originally Posted by Greymalkin

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

I get:





Book answer is:

You textbook is mistaken.

Originally Posted by a tutor

You're nearly right. The answer is 4i.

It appears I was overhasty in posting this because I've mixed up the answers from the text, the actual answer says 4, why would you say it is 4i? isnt i*0=0?

Originally Posted by Greymalkin

It appears I was overhasty in posting this because I've mixed up the answers from the text, the actual answer says 4, why would you say it is 4i? isnt i*0=0?

Because before you edited it the answer was 4i.

It also appears that my brain isnt into math on fridays

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 .

Originally Posted by ILikeSerena

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 .

Sorry, the real question is (1-i)(2+2i). Although my question was answered my editing was not finished, apologies.