I'm using the fx-cg50 and doing problems regarding polar graphs. I have my variables in terms of theta but I cannot figure out how to do d(theta) instead of dx when you hit options and clac in the graph mode. I would really appreciate help from some who know how to change it.

# Problem with differentiation with respect to theta

### #1

Posted 26 March 2022 - 02:05 PM

### #2

Posted 26 March 2022 - 02:20 PM

As far as I would understand:

You are in Graph Mode (Menu -> 5).

You are using r = <term>.

You want to use differential/integration in OPTN -> Calc Menu.

In the casio docs for differential/integration (Go to SHIFT -> 4 Catalog -> <your command> -> QR) it is stated that you can only use "X" as the variable. That cannot be changed.

What's the problem? just use X instead in your formula.

The Graph editor uses an X/x if you have Y = <term> and (theta) for r = <term>.

The differential uses X/x for calculation.

**Edited by HappyCalc, 26 March 2022 - 02:22 PM.**

### #3

Posted 26 March 2022 - 02:53 PM

https://www-fourier....nstall_en#casio

There you can use

diff(<term>,<var>) for differential,

plot(<term>,<var>) to show a y= graph and

plotpolar(<term>,<var>) to show a r= graph.

For example try this:

r:=sin(2*theta)

rd:=diff(r,theta)

plotpolar(rd,theta)

That would draw cosine wave in polar coordinates. You can change the variables to whatever you want. You can also name them foo, bar, baz...

### #4

Posted 26 March 2022 - 03:43 PM

here's the equation I was trying to enter into my calculator:

https://www.desmos.c...ator/0hqtm8mw1u

### #5

Posted 26 March 2022 - 03:59 PM

What is exactly your problem?

As far as I would understand:

You are in Graph Mode (Menu -> 5).

You are using r = <term>.

You want to use differential/integration in OPTN -> Calc Menu.

In the casio docs for differential/integration (Go to SHIFT -> 4 Catalog -> <your command> -> QR) it is stated that you can only use "X" as the variable. That cannot be changed.

What's the problem? just use X instead in your formula.

The Graph editor uses an X/x if you have Y = <term> and (theta) for r = <term>.

The differential uses X/x for calculation.

I can't use x when using r = <term>. and the graph becomes a straight line if I use Y = <term>

### #6

Posted 31 March 2022 - 05:44 AM

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