11-2

This week I am going to teach you all chapter 11 section 2. The problems in this section use complex numbers. There are several formulas that you need to know so that you can work problems in this section.
The formulas are as follows:
• z = x + yi
• z = r cos theta + r sin theta i
• z = r cis theta
• z = square root of ( x^2 + y^2 )
Remember, when multiplying complex numbers:
• To multiply rectangular equations, use FOIL
• To multiply polar equations, multiply r and add theta
Now I will show you an example of how to do one of these problems.
Example: Change ( 3, 3 ) from rectangular to polar
• r = sq. root of ( 3^2 + 3^2 )
• r = +/- 3 sq. root (2)
• theta = tan^-1 (3/3)
• theta = 45 degrees, 225 degrees
Your final answer would be (3 sq. root of 2, 45 degrees) and (-3 sq. root of 2, 225 degrees)

-Braxton-