How do I know if my calculator is in radians or degrees?
Look at the top of the screen. fx-991EX: the indicator at the top shows the angle unit.fx-991CW: the status bar shows the angle unit.fx-CG50: the status bar shows Deg or Rad.Or type sin(90): 1 means degrees; 0.894 means radians.
A trig answer that is badly wrong is nearly always the wrong angle mode. The quickest test, on any calculator: work out sin(90). An answer of 1 means degrees; 0.894 (to 3 s.f.) means radians.
When do I need radians, and when degrees?
Use degrees. The Edexcel 4MA1 specification says radian measure is excluded (sectors, 4.9), and the Cambridge 0580 syllabus does not use radians. If your calculator shows R or Rad, switch it back to degrees.
Source: Pearson Edexcel International GCSE Mathematics A (4MA1) specification, Issue 2 (PDF) · Cambridge IGCSE Mathematics 0580 syllabus 2025–2027 (PDF)
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Pick your calculator: the page remembers it next time.
How do I know if my fx-991EX is in radians or degrees?
An indicator at the top of the screen shows the current Angle Unit (degree, radian or gradian).
How do I change the fx-991EX to radians or degrees?
- Press SHIFT MENU (SETUP).
- Press 2 (Angle Unit).
- Press 1 (Degree) or 2 (Radian).
Source: Casio fx-991EX / fx-570EX User's Guide (PDF) · Casio fx-991EX Quick Start Guide (PDF)
How do I know if my fx-991CW is in radians or degrees?
An indicator in the status bar at the top of the screen shows the current Angle Unit (degree, radian or gradian).
How do I change the fx-991CW to radians or degrees?
- In a calculator app, press SETTINGS.
- Choose Calc Settings → Angle Unit.
- Choose Degree or Radian.
Casio's guide: when a derivative or integral has a trig function in it, set the Angle Unit to Radian.
Source: Casio fx-991CW User's Guide: Using the SETTINGS Menu
How do I know if my fx-CG50 is in radians or degrees?
Look at the status bar at the top of the screen: it shows Deg, Rad or Gra.
How do I change the fx-CG50 to radians or degrees?
- Press SHIFT MENU (SET UP).
- Move down to Angle.
- Press the function key for Deg or Rad, then EXIT.
Source: Casio fx-CG50 Software User's Guide (PDF): SET UP and Reset · Casio UK: Getting started with the fx-CG50, guide for teachers
How do I know if my TI-84 Plus CE is in radians or degrees?
The status bar at the top of the screen shows RADIAN or DEGREE.
How do I change the TI-84 Plus CE to radians or degrees?
- Press mode.
- Move down to the RADIAN DEGREE line.
- Move across to the one you want and press enter.
How do I know if my TI-Nspire CX II is in radians or degrees?
The angle mode (RAD or DEG) is shown at the top of the page you are on.
How do I change the TI-Nspire CX II to radians or degrees?
- Press home/on and choose Settings → Document Settings.
- Set Angle to Radian or Degree.
- Choose OK.
Graphs and Geometry pages have their own angle settings: TI says the Graphing Angle starts as Radian and the Geometry Angle as Degree. Set them to Auto to follow the document's angle.
Source: TI-Nspire CX Student Software Guidebook: Document Settings · TI-Nspire guidebook: Changing Graphs & Geometry Settings
Questions
How do I know if my calculator is in radians or degrees?
Look at the top of the screen: the calculators on this page show the angle unit there. Or work out sin(90): 1 means degrees, 0.894 means radians.
How do I change the fx-991EX to radians?
Press SHIFT MENU (SETUP). Press 2 (Angle Unit). Press 1 (Degree) or 2 (Radian).
How do I change the fx-991CW to radians?
In a calculator app, press SETTINGS. Choose Calc Settings → Angle Unit. Choose Degree or Radian.
How do I change the fx-CG50 to radians?
Press SHIFT MENU (SET UP). Move down to Angle. Press the function key for Deg or Rad, then EXIT.
How do I change the TI-84 Plus CE to radians?
Press mode. Move down to the RADIAN DEGREE line. Move across to the one you want and press enter.
How do I change the TI-Nspire CX II to radians?
Press home/on and choose Settings → Document Settings. Set Angle to Radian or Degree. Choose OK.
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Sources
Every keystroke on this page comes from the manufacturer's own guide for that model, and every exam rule from the exam board's own document; each section names its source. Where we could not find a step in one of those documents, we have left it out. IGCSE Math Revision is independent and is not connected to Casio, Texas Instruments or any exam board.