Geometry app

[Tugdual]

I’m a bit puzzled with the geometry app. It looks quite buggy and limited. What is the general opinion? Was looking for a way to create a line having a given angle witn an existing line and eventually found no other way but create a rotation. I’m quite new to this app, am I missing something?

[ijabbott]

I'm not sure which calculator has the best geometry app. Possibly the Casio fx-CP400 or fx-CG500 because of its relatively large screen?

[cyrille de brébisson]

hello,

Geometry app has some limitations, but should work rather well apart from that.
The Geometry app is basically a graphical interface on top of the CAS geometry related functions.

The geometry app is basically a CAS program using the CAS geometry functions...
each line in the symbolic view is basically executed as a CAS program line as a GNAME:= instruction... call..
Once you understand that, you should understand most of what the geometry app is.

Cyrille

[Tugdual]

(09-23-2019 04:58 AM)cyrille de brébisson Wrote:  hello,

Geometry app has some limitations, but should work rather well apart from that.
The Geometry app is basically a graphical interface on top of the CAS geometry related functions.

The geometry app is basically a CAS program using the CAS geometry functions...
each line in the symbolic view is basically executed as a CAS program line as a GNAME:= instruction... call..
Once you understand that, you should understand most of what the geometry app is.

Cyrille

Thanks Cyrille, I was expecting something like CaRMetal when I saw the interface. While you can create a perpendicular line why can’t you pick any other angle but pi/2?
Is this app being developed or state of the art?

[Tim Wessman]

(09-23-2019 06:08 AM)Tugdual Wrote:  Thanks Cyrille, I was expecting something like CaRMetal when I saw the interface. While you can create a perpendicular line why can’t you pick any other angle but pi/2?

Um, isn't "perpendicular" by definition pi/2 or 90 degrees?

[Tugdual]

(09-24-2019 02:04 AM)Tim Wessman Wrote:  

(09-23-2019 06:08 AM)Tugdual Wrote:  Thanks Cyrille, I was expecting something like CaRMetal when I saw the interface. While you can create a perpendicular line why can’t you pick any other angle but pi/2?

Um, isn't "perpendicular" by definition pi/2 or 90 degrees?

Indeed and my question is about having another angle but pi/2
Like I want 2 lines 63° angle.

[parisse]

What's wrong with using a rotation in this case?
By the way, you can create your own CAS function and use it in the geometry app, but I can't imagine something simpler than using a rotation.

[Dave Britten]

(09-22-2019 11:27 PM)ijabbott Wrote:  I'm not sure which calculator has the best geometry app. Possibly the Casio fx-CP400 or fx-CG500 because of its relatively large screen?

I particularly like the geometry app on the Prizm (and also the fx-9860G series, which is basically the same app but with a lower-resolution monochrome screen). It's constraint based, meaning you can specify properties and relationships that must be satisfied. So for example, you could define a line segment, and constrain one endpoint's coordinates to (0,0), and constrain the length to 2. Then define another line segment with one endpoint at (0,0), and constrain the angle between the two segments to 30 degrees. Then if you drag the outer endpoint of either line segment, the other segment will rotate with it to maintain the 30-degree angle.

[Tugdual]

(09-25-2019 01:25 PM)parisse Wrote:  What's wrong with using a rotation in this case?
By the way, you can create your own CAS function and use it in the geometry app, but I can't imagine something simpler than using a rotation.

The rotation clones an existing object and providing that the app is quickly bloated with too many objects (even on a G2) this is not desirable.
DGPad is actually a very good exemple of what a geometry app can be on a touch screen.

[parisse]

(09-26-2019 05:46 AM)Tugdual Wrote:  

(09-25-2019 01:25 PM)parisse Wrote:  What's wrong with using a rotation in this case?
By the way, you can create your own CAS function and use it in the geometry app, but I can't imagine something simpler than using a rotation.

The rotation clones an existing object and providing that the app is quickly bloated with too many objects (even on a G2) this is not desirable.

I don't understand what you mean. You can create your new line with exactly one command: new_line:=rotation(point_on_line,angle,line). How can it be simpler?
Maybe you are used to other geometry app, and you don't like the philosophy ot the Prime geo app, but please consider that it's your point of view, it's not something intrinsic.
The Prime geometry app is an analytic geometry app (like Geogebra is), you build your construction exactly like you would make a program to compute something with scalars, except that here you will have all intermediate objects displayed. And you can do *exact* analytic geometry, something you will not find on other geometry apps (at least on a calculator), that means you can *prove* geometry theorems.

[cyrille de brébisson]

Hello,

To echo Bernard's statement...

The Prime geometry app is NOT a "drawing" app, but a math app, and I think that it makes a big difference in this type of things...

When I want to make a technical drawing (like using 3DsWorks), I use a lot of what you are talking about because what I am interested in is the end drawing.

When I use the geometry app, it's to make a mathematical proof, and at this point, the Prime app is well adapted...

Some problems, of course, are kind of on the boundary sometimes, blurring the line.

Cyrille

[Tugdual]

I was not confused with a drawing app. DGPad is exactly what you describe Cyrille and while I discovered it 2 days ago (hence it is not my top legacy favorite app I'm used to) on iPad, it is even available online DGPad
Starting with a blank screen is a bit baffling and DGPad doesn't have much online doc but definitely worth the exploration. I mentioned it because it is a very good app aimed to support touch screen at the first place. Very light as well and this is another issue with the App on the Prime: it is quickly bloated, I see the hourglass and the calc is stuttering...