Expressing a complex number in cartesian form

Im stuck on a textbook question that has no previous examples. Express in cartesian form.

OK. So i know De moivre's Theorem but not sure if i can use it here (and thats going away from Cartesian form too)

But could I say that here the form r(cos x + isin x) can be deduced because is and then deduce sin.....

But not sure where to go from here!...

Re: Expressing a complex number in cartesian form

Quote:

Originally Posted by

**FelixHelix** Im stuck on a textbook question that has no previous examples. Express

in cartesian form.

OK. So i know De moivre's Theorem but not sure if i can use it here (and thats going away from Cartesian form too)

But could I say that here the form r(cos x + isin x) can be deduced because

is

and then deduce sin.....

But not sure where to go from here!...

Re: Expressing a complex number in cartesian form

Quote:

Originally Posted by

**FelixHelix** Im stuck on a textbook question that has no previous examples. Express

in cartesian form....

Now apply De moivre's Theorem.

Re: Expressing a complex number in cartesian form

I'm confused by the workings here. Could you explain how you get the original argument here?

Re: Expressing a complex number in cartesian form

HI Plato, Im confused, how come your workings are different to Princeps? and how do you get r = 2 in your polar form here?

Re: Expressing a complex number in cartesian form

Quote:

Originally Posted by

**FelixHelix** HI Plato, Im confused, how come your workings are different to Princeps? and how do you get r = 2 in your polar form here?

They are not different; they are equivalent. You should know that.

I just prefer the principal argument, .