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Trigonometry

Set degrees or radians

Tell the calculator whether angles are measured in degrees or radians before you use sin, cos or tan.

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Every trig key needs to know what unit your angle is in. A full turn is 360 degrees or 2π radians. If the mode does not match your numbers, the answer will look wrong even though the calculator did exactly what you asked.

A quick test: sin(30) must give 0.5 in degree mode. If you see -0.988 instead, the calculator is in radian mode.

Classic Graphing 84

Start on the main screen: Press 2nd then mode (QUIT) to get back to the home screen. Pressing clear on a menu also backs out of it.

  1. Open the mode screen. Move down two lines to the angle row, move right onto DEGREE and press enter to choose it. Then leave the screen.

    mode▼▼▶enter2ndQUITmode

  2. Test it: sin(30) should be 0.5.

    sin30)enter

You should seesin(30) .5

Classic Graphing 84 key reference

Classic Scientific 30

Start on the main screen: Press 2nd then mode (QUIT) to leave any menu or screen and return to the calculation screen.

  1. Open the mode screen. The top row holds DEG, RAD and GRAD. Press enter on DEG, then leave the screen.

    modeenter2ndquitmode

  2. Test it: sin(30) shows the exact value 1/2.

    sin30)enter

You should seesin(30) 1/2

Classic Scientific 30 key reference

Natural Scientific 991

Start on the main screen: Press MENU, then 1 (Calculate) to return to the main calculation screen. AC clears the line you are on.

  1. Open the setup menu (SHIFT then MENU) and pick 2, Angle Unit. Then choose 1 for Degree.

    SHIFTSETUPMENU21

  2. Test it: sin(30) should be 1/2.

    sin30=

You should seesin(30 1/2

Natural Scientific 991 key reference

Natural Color Graphing

Start on the main screen: Press MENU then 1 to open Run-Matrix, the main calculation screen. Press EXIT to back out of a bar or screen, and SHIFT then EXIT (QUIT) to return to the app start.

  1. Open SET UP (SHIFT then MENU). Move down to the Angle line and press the F2 key under Deg. Press EXIT to go back.

    SHIFTSET UPMENU▼▼F2EXIT

  2. Test it: sin(30) should be 1/2.

    sin30EXE

You should seesin(30 1/2

Natural Color Graphing key reference

Classic CAS

Start on the main screen: Press home to open the Home menu (Calculator, Graphs, Settings, and more). Choose Calculator, or press esc to go back to the calculation page.

  1. Open Settings from the menu key (option 9). Move down to Angle, right to Degree, and confirm with enter.

    menu9▼▶enterenterenter

  2. Test it: sin(30) should be 1/2.

    sin30)enter

You should seesin(30) 1/2

Classic CAS key reference

RPN Scientific 15

Start on the main screen: There is no menu to leave. Press the back arrow to clear a number you are typing, or CLx (g then back arrow) to clear the X register.

  1. Press g, then 7 to select DEG.

    gDEG7

  2. Test it: key in 30 and press SIN. The answer is 0.5.

    30SIN

You should see0.5000

Press g then 8 for radians. This model starts in degrees.

RPN Scientific 15 key reference

RPN Advanced 42

Start on the main screen: Press EXIT (once or twice) to close any menu and return to the plain stack view of Y and X.

  1. Open the modes menu with the shift key and +/−. The menu keys along the top choose DEG, RAD or GRD. Press the first one for degrees.

    ⇧MODES+/−Σ+

  2. Test it: key in 30 and press SIN.

    30SIN

You should seex: 0.5000

RPN Advanced 42 key reference

RPN Power 48

Start on the main screen: Press ON to cancel what you are typing, then use the stack view. Open the MODE or VAR menu any time; the stack is always shown above the menu row.

  1. Press MODE. The row of menu keys now shows DEG and RAD. Press the fifth one, DEG.

    MODEF5

  2. Test it: key in 30 and press SIN.

    30SIN

You should see1: .5

This model starts in radians. The header line shows RAD or DEG so you can always check.

RPN Power 48 key reference

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