I am all if favor of an arc that matches Rhino’s: center, start, end.
If you want something similar to Rhino you can use Arc component from Params > Geometry
Or you can use the python script from this topic with start/end points and radius
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Thank you Seghier khaled, but…
But …?
But I wish we had a built in Rhino-style arc.
(Ducks)
I don’t know, this Arc component work exactly like Rhino
Maybe you will see your request in the future Grasshopper
thank you @anon39580149 pretty clear!
and how about if now I have ARC Lenght and Distance defined and I want to calculate the sagitta “H”?
Best
T.
Distance(Chord) >> D
H/0.5*D = tan(a) >> H = 0.5*D*tan(a)
We replace it in the equation: a-(0.5*L*sin(a)²/H) = 0
We get: a-(L*sin(a)*cos(a)/D) = 0
And we use the same way to find the solution
ARC_distance_solver_2.gh (25.0 KB)
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thank you for your time and the explanation @anon39580149!
Since you work in python, does this happen to you as well?
I don’t know about this , sometimes when i put new component in the canvas i see for example 35ms ,when i click recompute the message disappears, not only with python
You can ask the developers in a new topic
hey, many thx for this pythono component … i am wondering how to set the orientation plane of the arc. it constructs the arc on the XY plane i need it on the ZY plane and am to nooby to figure out how to do it 
i played around with some other parameters in the definition and suddenly the arcs are oriented ZY like i want it, i have no idea what i did so that it switched, would love to understand 
it seems to switch planes randomly, when i open the definition the arcs are always on XY but at some point they change and i can’t figure out how to set them to ZY consistently.
Hi
There is no option to add plane in rhinoscriptsyntax , you can rotate the arc around the center of the line between the two points
ArcPPR_.gh (11.3 KB)
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hey thanks … i didn’t even think of rotating 
i am using the orient component now since for some reason the orientation of the arc still flips around from time to time, i have no idea why or what triggers it. even the orient component wouldn’t stick until i rebuild it from scratch. now it seems to stick finally.
hello @anon39580149 i opened up my patch with your script today after a Rhino update and i got an error that python was missing (i forgot to take a screenshot so don’t remember the exact message). i clicked the download and install button but got an error that the package was not available.
the previously used component come up as white boxes but i can still use your component by inserting it again.
not sure what’s going on there …
i can’t select or delete the white box at all, i can’t even move it, as you can see it’s inside a group (the purple box) but when i move the group only the other elements move, the white box stays stuck in place.
In the photo Ghpyton is loaded, where is the problem?
Can you share ypur file
yeah it’s weird, i could load another instance of your script and reconnect the inputs and outputs to that so my patch is working again. i just can’t get rid of the old component and don’t understand why it threw the error in the first place since obviously ghpyton is installed and working.
unfortunately i can’t share the file, since it’s a production file of a commercial design, never seen this white unmovable unselectable box before
Hi Chris -
That is a placeholder that shows up on a system where a certain plug-in is not installed.
The ArcPPR_.gh file that was posted here earlier opens fine here. Without your file, it’s hard to know what goes wrong…
-wim
Copy the file and remove all components, this will leave only the placeholder.
This way we can know this missing component
ok here’s the file with everything removed but the missing plugin component.
missingplug_arcdebug.gh (2.8 KB)
thanks again for your quick help. As i said i managed to repair my patch by just re-inserting and reconnecting the inputs/outputs of the fresh component. Ghpython was installed all along and i didn’t even have to reinstall the ArcPPR_.gh file so not sure what happened when Rhino prompted me that the plugin was missing when i opened the file.
