Introduction to converting complex numbers into trigonometric form.

1. 6.5 Complex Numbers in
Trigonometric Form
Objectives:
1) Convert complex numbers to trig form
and vice versa
2) Multiply/Divide complex numbers in trig
form.
Standard: Math Analysis 2.0

2. Ex. 1) Given: –2+4i
a) Graph
b) |–2+4i|
c) Find the inclination

3. Ex. 2) Given r=5 and θ=142°, find the
complex number a+bi at the same location.

4. θ
b
a
r

5. Trig Form Complex Form

6. Ex. 3) Write 6–6i in trig form.

7. Ex. 4) Write as a complex number.

8. Multiplying Complex Numbers in
Trig Form
Standard Form: (a+bi)(a+bi) = FOIL
Trig Form:

9. Ex. 5) Find z1z2.

10. Dividing Complex Numbers in
Trig Form
Standard Form: (a+bi)÷(a+bi)
= multiply by conjugate
Trig Form:

11. Ex. 6) Find

12. Assignment:
#6 p. 478
#12-39 (mult. of
3), 47-57 (odd)