Chapter 11-3

Soo today, we are going to learn all about De Moivre’s theorem! As I said in an earlier blog, chapter 11 consists of a few formulas to be followed. Most of them are really easy. (Especially in this section because there is only one that you must know J) It is pretty simple if you follow the theorem exactly how it is stated. There is one thing that you need to keep in mind throughout this section and that is:

**DO NOT DRAW ARGAND DIAGRAMS**

De Moivre's theorem states the 2=rcisø then z^n=r^n cis(nø)

So now for the emphasis example!

Evaluate (2sin45)^2

1. z^2=2^2cis2(45)
2. z^2=4cis90

Since I don't think I hit a 150 words yet, I'll do a problem like this but working backwards.

z=4cis20º (Use De Moivre's theorem to find z^3)

1. z^3=(4)^3cis(3(20))
2. z^3=64cis60

So basically if you know and learn De Moivre's theorem, you can work any of these problems.

Hope you learned something!

Carleyyyy :)