TI-84 documentation

Trigonometry on a TI-84 Calculator

Match the angle mode to the problem, then use direct or inverse trig functions correctly.

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Match the angle mode to the problem, then use direct or inverse trig functions correctly.

1Set angle mode

2Evaluate trig functions

3Use inverse trig to find angles

Worked example

Follow the example values and compare your calculator display with the expected result shown below.

Set the correct angle mode

Press MODE and select Degree for degree measures or Radian for radian measures. The mode indicator appears at the top of the screen.

Evaluate a trig function

SIN30)ENTER

In Degree mode: sin(30) = 0.5.

Use inverse trig

To find an angle whose sine is 0.5, use 2nd → SIN (sin⁻¹).

2nd→SIN→0.5→ENTER

In Degree mode: 30°.

Worked right-triangle example

A right triangle has opposite side 6 and adjacent side 8. Find θ.

tan(θ)=6/8, so enter tan⁻¹(6÷8).

Expected result: θ ≈ 36.87°.

Parentheses matter: enter tan⁻¹(6÷8), not tan⁻¹(6)÷8.

Practice

In Degree mode, evaluate cos(60).

Reveal the answer

0.5.

Practice with the calculator open

Use the guide in one tab and the calculator in another.

Open TI-84 Calculator

Editorial note: This guide is independently written for classroom practice and was reviewed against the TI-84 Plus CE guidebook. Button labels and menu availability can vary by model and operating-system version.

Last reviewed: July 17, 2026

Learning standard: worked example, expected result, troubleshooting and practice.

Angle and display modes

Degree and radian mode change the meaning of trigonometric input. The display setting controls how many decimal places appear, but it does not change the stored precision used by the calculator.

Before a trigonometry problem

Read the problem for a degree symbol or a radian measure.
Open MODE and select the correct angle setting.
Evaluate a familiar value such as sin(30) in Degree mode to confirm the setup.

Use normal display for most classroom work unless the question asks for a fixed number of decimal places or scientific notation.