WhiteningProving de Moivre's Formula for Complex Numbers?

[Vitani11]

Homework Statement

Picture has been uploaded with question.

Homework Equations

The Attempt at a Solution

I have literally never seen anything like this in my life. I'm in mathematical physics. I looked up de Moivre's formula and I guess this comes from a course in complex variables? I don't know why this is a homework question given that nobody in my class has actually taken it, but whatever. I need to be able to prove this. Can you please help me out, where should I start? I am familiar with geometric series and I guess I can reference De Moivre's formula. That's where I'm at. My initial thought was that this had something to do with a taylor expansion, but I know cos(x)'s taylor expansion and I don't think that has anything to do with this.

 

[TeethWhitener]

Write out de Moivre's formula and see if it has the same form as one of the summands you're given.

 

[LCKurtz]

Can you please help me out, where should I start?

Start by posting an image that is right side up.

 

[Ray Vickson]

Start by posting an image that is right side up.

Better still: do not post an image at all; type out the problem (the much preferred PF way).

 

[Vitani11]

Okay.

 

[Vitani11]

Got it, thank you Teeth