Section 11: Calculating With Complex Numbers 135

Example: Find the sum 2(cos 65° + i sin 65°) + 3(cos 40° + i sin 40°) and express the result in polar form, (In phasor form, evaluate 2 ∠ 65° + 3 ∠ 40°.)

Keystrokes

Display

D

 

2 v

2.0000

65 ´V

2.0000

´;

0.8452

3 v

3.0000

40 ´V

3.0000

´;

2.2981

+3.1434 : 4.8863

´% (hold) 49.9612 (release) 4.8863

Sets Degrees mode for any polar- rectangular conversions.

C annunciator displayed; Complex mode activated.

Converts polar to rectangular form; real part (a) displayed.

Converts polar to rectangular form; real part (a) displayed.

Converts rectangular to polar form; r displayed.

θ(in degrees).

Problems

By working through the following problems, you will see that calculating with complex numbers on the HP-15C is as easy as calculating with real numbers. In fact, once your numbers are entered, most mathematical operations will use exactly the same keystrokes. Try it and see!

2i (−8 + 6i)3

1. Evaluate:

(4 − 2 5 i) (2 − 4 5i)