Angle Conversions on the TI-89

You should be able to convert between radians and degrees quickly and efficiently without a calculator. However the TI-89 can be useful in checking your work and allowing you to make up and check practice problems on your own.

Angle Mode on the TI-89:

You can tell whether the TI-89 is currently using radians or degrees by checking the status line on the home screen.
You can change the angle mode by pressing the key and opening the angle sub-menu.

Converting Radians to Degrees on the TI-89:

If your TI-89 is in radian mode, first type the radian value, then open the Math menu (press 2nd key5 key), choose the angle sub-menu (press 2 key), then select either "8: DMS" or "9: DD" and press Enter key.

(Instead of using the Math menu, you press 2nd keyMode key to get the conversion symbol, and then type "DD" or "DMS" from the keyboard, or select the function from the Catalog key.)

The "DD" function returns the angle in exact degrees when you press Enter key (the upper result at right), or a decimal approximation when you press Diamond keEnter key (the lower result at right).
The "DMS" function returns degrees, minutes, and seconds. The Enter key result is the upper one at right, and the Diamond keEnter key result is the lower result at right.

If your TI-89 is in degree mode, you can still indicate that a value is in radians. Following the value, access the Math menu (press2nd key 5 key) and select "2: r" from the angle sub-menu (press 2 key2 key), then enter the conversion function "DD" or "DMS" (see above).

(Note the parentheses around the value on the status line in the screen shot at right. What happens if you don't use them?)

Converting Degrees to Radians on the TI-89

If your TI-89 is in degree mode (check the status line in the screen shot at right), first type the degree value, then open the Math menu (press 2nd key5 key), choose the angle sub-menu (press 2 key), then select "B: Rad" (press Alpha keyParenthesis key) and press Enter key.

(Instead of using the Math menu, you press 2nd keyMode key to get the conversion symbol, and then type "Rad" from the keyboard, or select the function from the Catalog key.)

Of course, you can get a decimal approximation by pressing Diamond keEnter key (not shown).

If your TI-89 is in radian mode (check the status line in the screen shot at right), you can still indicate that a value is in degrees. Following the value, access the Math menu (press2nd key 5 key) and select "1: o" from the angle sub-menu (press 2 key1 key), then enter the conversion function "Rad".

last update December 5, 2008 by JL Stanbrough