x Turn on thread page Beta
 You are Here: Home >< Maths

# de Moivre question watch

1. using de moivre Theorum we know that:

Z^n = cos(nø) + isin(nø)

Z^-n = cos(nø) - isin(nø)

I thought it would be:

Z^-n = cos(-nø) + isin(-nø)
2. cos(-x)=cos(x)

sin(-x)=-sin(x)
3. (Original post by Sifr)
using de moivre Theorum we know that:

Z^n = cos(nø) + isin(nø)

Z^-n = cos(nø) - isin(nø)

I thought it would be:

Z^-n = cos(-nø) + isin(-nø)
It is! But you can simplify that using cos(-A) = cos A etc.

TSR Support Team

We have a brilliant team of more than 60 Support Team members looking after discussions on The Student Room, helping to make it a fun, safe and useful place to hang out.

This forum is supported by:
Updated: March 20, 2013
Today on TSR

### How do I turn down a guy in a club?

What should I do?

Poll
Useful resources

### Maths Forum posting guidelines

Not sure where to post? Read the updated guidelines here

### How to use LaTex

Writing equations the easy way

### Study habits of A* students

Top tips from students who have already aced their exams