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Theta (θ) is the eighth letter of the Greek alphabet and a common symbol in mathematics. While it doesn’t have a fixed meaning, it is often used as a variable for angles and polar coordinates. Its interpretation depends on the context.

1. Turn on Your TI‑84

Press the On key. When the information box appears, press 1 to continue to the home screen and suppress the box on future startups, or press 2 to simply go to the home screen.

2. Switch to Polar Mode

The θ key is available only when the calculator is in Polar mode. Press the Mode key (top row). Use the ↓ arrow to scroll until you see the line “Function Parametric Polar SEQ.” Then use the → arrow to highlight Polar and press Enter. In Polar mode, the radius (r) is a function of the angle (θ).

3. Insert the Theta Symbol

With the calculator in Polar mode, you can now enter θ:

• Press the 2nd key (the secondary function key).
• Press the key labeled θ (located above the number 2).
• The symbol will appear in the expression entry area.

Once inserted, you can use θ in equations, parametric plots, and other calculations that require polar coordinates.