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How to multiply complex numbers for AC circuits on a TI-89 Titanium

By E-Code · updated

Type the complex numbers with 2nd CATALOG for ί and press ENTER: (3.+4.ί)*(1.-2.ί) gives 11.-2.·ί. Press ▶, then 2nd MODE for ▶, type Polar and ENTER to see it as size and phase, (11.1803∠-10.3048) in degree mode.

Before you start

Set Angle to DEGREE in MODE first.

MODE ▼ ▼ ▼ ▶ 2 ENTER

Step by step

  1. Type Z times I. ( 3 . + 4 . 2nd CATALOG ) × ( 1 . − 2 . 2nd CATALOG ) Type (3.+4.ί)*(1.-2.ί): an impedance of 3+4ί ohms times a current of 1-2ί amps. 2nd CATALOG types ί.
  2. Multiply. ENTER Press ENTER. The TI-89 multiplies complex numbers like any others.
  3. Keep the line. ▶ Press ▶ to put the cursor at the end of the last entry.
  4. Type ▶ (convert). 2nd MODE Press 2nd, then MODE for ▶. It means show this as.
  5. Type Polar. 2nd ALPHA STO→ − 4 = 2 ALPHA Press 2nd ALPHA to lock letters, type p o l a r (STO→ − 4 = 2), then ALPHA to unlock.
  6. Show size and phase. ENTER Press ENTER.
  7. Read the voltage. V = 11-2ί volts, or 11.18 V at a phase of -10.3°: the size a meter shows and how far it lags.

What the screen shows

V = 11-2ί volts, or 11.18 V at a phase of -10.3°: the size a meter shows and how far it lags.

Look for (11.1803∠-10.3048) on the screen.

Try it with the keys lit up

This guide is one of E-Code's Learn lessons. Open it on E-Code's TI-89 calculator and each key lights up in turn as you press it.

Try “Multiply complex numbers for AC circuits” on the TI-89 calculator

Related

Engineering programs for the TI-89 Titanium:

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