# Spherical Trigonometry

brocks shared this idea 7 years ago
Under Consideration

Since it now has 3D capability, it would sure be nice if Geogebra did spherical trig. Even something as simple (says the guy who is clueless about how hard it would be to implement) as drawing great circle arcs on spheres, and giving the angle measures of the resulting triangles, would be very helpful for my astronomy hobby. Thank you.

1

Hey !

I don't know how hard it would be to add these new tools to the GeoGebra library (I think it would'nt be so hard actually since they've already created the "custom tool" menu). So you can already create the tools you need on your own. You just have to manually create all the results you need step by step. Then select new custom tool and enter the initial and final objects.

Try to format the name of your function with something like SphericalArc (starts with uppercase letter every words). (Initial object would be the two points on sphere and the sphere center, final would be the arc or circle).

Eventually, you'll just have to import your new tool in your future constructions.

(custom tool tutorial : http://wiki.geogebra.org/en...)

Would you post your new tool right here ? I'll be glad to see that.

1

Hi,

with GeoGebra, it's very simple !

move point A or B

https://ggbm.at/850775

1

Ca répond en partie à sa question. : )

Je crois qu'il veut aussi un 3e point de façon à tracer un triangle (en arcs) sur la sphère, et pouvoir récupérer les angles de ce triangle.

1

Hi,

peut être quelque chose comme ça ?

Maybe something like that ?

https://ggbm.at/1388167

1

I apologize for not responding sooner; I was called away for a family emergency.

Thank you all very much for the responses. I was not aware of some of the commands available, as I am still a beginner, but the CircularArc command does seem to work well. It would be nice, though, if there was a Spherical Trig mode that assumed that all arcs were centered on the center of the sphere.

Also, using the Angle command to get angles on the surface of the sphere, rather than measured from the center of the sphere, requires using tangents as shown by Patrick, which is very unwieldy. Again, a Spherical Trig mode that did that automatically would be very helpful.

As suggested, I will try to learn how to create such tools, and will post them if I am successful.

Thanks again for the very helpful responses.