Which steps with my calculator are needed to obtain result in radians?

[mcastillo356]

TL;DR

I've read more than one time the guideline, but not obtained the result related to $\pi$

Hi PF, hope to be publishing in the right forum
<moderator's note: moved to the right forum >
$\arccos{\dfrac{\sqrt{2}}{2}}\mbox{rad}=\dfrac{\pi}{4}\mbox{rad}$
This is a trigonometric true, but I've read the steps in my guideline, and I don't manage. The calculator is a chinese Kooltech CPC-400N, an imitation of Casio fx-82MS. It should work similarly.
I enter the data, and the result is 0,785398163. Right, but, how could I obtain $\dfrac{\pi}{4}$?
Greetings!

 

[DrClaude]

The calculator makes numerical computations, not symbolic ones. To get the results in terms of π, you have to divide by it.

 

[mcastillo356]

Thank you very much, DrClaude! Understood. Divided by $\pi$, $0,249999999\Rightarrow{\dfrac{\pi}{4}}$
Greetings!
PD: You meant multiply and divide by $\pi$, isn't it?

 

[DrClaude]

Thank you very much, DrClaude! Understood. Divided by $\pi$, $0,249999999\Rightarrow{\dfrac{\pi}{4}}$
Greetings!
PD: You meant multiply and divide by $\pi$, isn't it?

You divide by π to get the multiplicative factor to apply to π.

 

[Wrichik Basu]

I enter the data, and the result is 0,785398163. Right, but, how could I obtain $\dfrac{\pi}{4}$?

You can't if you use Casio fx-82MS (or a clone) that has S-VPAM. For displaying fractions, you need a calculator with a natural textbook display (natural-VPAM), like fx-991ES plus.

(Sorry for the bad image quality)

 

[mcastillo356]

Thank you, Wrichik Basu (good image)!
DrClaude, I've understood: if I divide by $\pi$, the result is how many times 0,785398163 contains $\pi$. Left aside my poor english, I'm I right?

 

[DrClaude]

DrClaude, I've understood: if I divide by $\pi$, the result is how many times 0,785398163 contains $\pi$. Left aside my poor english, I'm I right?

Yes.

 

[Lnewqban]

 

[mcastillo356]

Thank you very much, Lnewqban! Still there is something I would like to ask... I will leave it for a while; I want to try if I can manage. It's another thread: how to calculate the unique phase of a complex number, that's it, $\mbox{arg}$ in the interval $(-\pi,\pi]$, $\mbox{Arg}$
Greetings!

 

[Lnewqban]

You are welcome, Castillo.
Sorry, I know nothing about argument.

 

[mfb]

Some calculators have an atan2 function or similar that takes care of the sign, otherwise you need to do that manually. Calculate the arctangent of (imaginary part/real part) and then add/subtract pi as needed based on the sign of the imaginary and real part.