How to Convert Rectangular to Polar in Casio Calculator: Step-by-Step Keystrokes

To convert rectangular to polar in Casio calculator models (such as the fx-991EX ClassWiz, fx-991CW, fx-82MS, and fx-300ES PLUS), use the built-in Pol( function. Press SHIFT followed by the [ + ] (Pol) button, type your horizontal coordinate $x$, press SHIFT and [ ) ] (comma), enter your vertical coordinate $y$, close the parenthesis with [ ) ], and press [ = ].

Figure 1: Complete button sequence and display output to convert rectangular to polar in Casio calculator series.

This feature calculates both the radial distance ($r$) and the polar angle ($\theta$) instantly while handling quadrant signs automatically. If you don’t have your scientific calculator nearby, you can use our free browser-based rectangular to polar converter for immediate calculations.

Model-by-Model Keystroke Guide for Casio Calculators

Different generations of Casio scientific calculators use slightly different menu structures. Find your model below for the exact keystrokes:

1. Casio fx-991EX ClassWiz & fx-570EX

The ClassWiz series displays high-resolution natural textbook displays with dual-line output:

[SHIFT] ➔ [+] (Pol) ➔ [x-value] ➔ [SHIFT] ➔ [ ) ] (,) ➔ [y-value] ➔ [ ) ] ➔ [ = ]

• Example Point $(4, 3)$:
  1. Press SHIFT then +. The screen displays Pol(.
  2. Enter 4.
  3. Press SHIFT then ) to produce the comma ,.
  4. Enter 3.
  5. Close parenthesis ) and press =.
  6. Display Output: r=5, θ=36.86989765

2. Casio fx-991CW & fx-570CW (New ClassWiz)

1. Ensure the calculator is in Calculate mode.
2. Press CATALOG $\to$ Coordinate Conversion $\to$ **Pol(`.
3. Enter x, press SHIFT $\to$ (,), enter y, press ).
4. Press EXE to display $r$ and $\theta$.

3. Casio fx-991ES PLUS / fx-82ES / fx-300ES PLUS

1. Press SHIFT then + (Pol).
2. Input x, press SHIFT then ) (,), input y, close ).
3. Press =.
4. Press the right arrow key ▶ to scroll and view $\theta$ if the screen truncates the angle.

4. Casio fx-82MS / fx-991MS / fx-100MS (Standard Two-Line Series)

1. Press Pol( directly (above the + key with SHIFT).
2. Type x $\to$ , (dedicated comma key) $\to$ y $\to$ ).
3. Press =. The screen displays $r$.
4. Press RCL then F (or tan) to display the angle $\theta$.

How to Recall and Reuse $r$ and $\theta$ from Memory

After executing Pol(x, y), Casio calculators automatically save the results into internal memory variables so you can use them in subsequent formulas:

Pro Tip: Reusing the stored $\theta$ variable prevents rounding errors when calculating complex AC circuits or phasor division!

Setting Angle Mode: Degrees vs Radians on Casio

Before running Pol(x, y), always ensure your calculator is set to your preferred angular unit:

1. For fx-991EX / ClassWiz:
   • Press SHIFT $\to$ MENU (SETUP).
   • Select 2: Angle Unit.
   • Choose 1: Degree (D symbol at top) or 2: Radian (R symbol at top).
2. For fx-991ES / ES PLUS:
   • Press SHIFT $\to$ MODE (SETUP).
   • Press 3 for Deg or 4 for Rad.

Reverse Conversion on Casio: Polar to Rectangular (Rec)

To convert polar coordinates $(r, \theta)$ back to rectangular $(x, y)$ on a Casio calculator, use the Rec( function:

[SHIFT] ➔ [-] (Rec) ➔ [r] ➔ [SHIFT] ➔ [ ) ] (,) ➔ [θ] ➔ [ ) ] ➔ [ = ]

• Example $(r=5, \theta=36.87^\circ)$:
  • Rec(5, 36.87) $\to$ Displays X=4, Y=3.

Troubleshooting Common Casio Coordinate Errors

• Syntax ERROR: You forgot the comma between $x$ and $y$ or missed the closing parenthesis. Remember to use SHIFT + ) for the comma.
• Unexpected Angle Value: The calculator was set to Radians instead of Degrees (or vice versa). Check the top of the display for D or R.
• Negative Coordinates: Use the negative sign key (-) rather than the minus subtraction key − when entering negative coordinates like Pol(-5, 12).

If you develop engineering software, educational platforms, or scientific calculation tools, explore the software engineering services at Shahab Dev.

Frequently Asked Questions (FAQ)

How do I convert rectangular to polar in Casio calculator fx-991EX?

Press SHIFT + + to open Pol(, enter your $x$ coordinate, press SHIFT + ) for a comma, enter your $y$ coordinate, close with ) and press =. The calculator outputs $r$ and $\theta$.

Where is the comma button on Casio calculators?

On most modern Casio models (fx-991EX, fx-991ES), the comma is located as a yellow shift function above the right parenthesis key ). Press SHIFT followed by ) to type ,.

How do I see the angle if it disappears from the screen?

On older two-line models (fx-82MS), the screen initially shows only $r$. Press RCL followed by F (or Y on ClassWiz) to view the angle $\theta$.

Can I convert complex numbers directly in Complex Mode?

Yes. On the fx-991EX, enter Menu $\to$ 2: Complex, type your complex number (e.g. 4 + 3i), press OPTN $\to$ scroll down $\to$ select 1: ▶r∠θ $\to$ press =. Learn more in our rectangular to polar circuits guide.