Beautiful Mind-Spherical Astronomy's Questions

[Fowad]

Hi dear knowledge seekers!
Here we can discuss about our ideas on spherical astronomy.any question,ambiguity,new idea,problems and etc.

As the first motivating action i ask a question:
If we choose 3 point on a sphere,We can half it in any way by this condition that all those 3 point be on one half!Why do you think?!
Hope you enjoy thinking about
 

[m-n-pour]

Hi Mr Motahari !
My answer to your Q :
As you know a sphere is 360 degrees , in fact ,a half of a sphere is 180 degrees (i) and imagine that you want to choose the points as far as possible from each other! What's the greatest distance between them ( two by two ) ?The answer is 180 degrees (ii) !!! (Why?) ,so as a result of (i)&(ii) we can notice that there is always a great circle which puts every 3 points on a sphere into one half of that sphere !! TanQ for this Q
Have a nice time
Best regards