Finding all sign combinations of a 3D point (x,y,z)

  • Level: High School 
  • Thread starter Thread starter Rosebud
  • Start date Start date
  • Tags Tags
    Combinations
Join the discussion
Registration is free. Start your own thread to ask a follow-up.
5 replies · 2K views
Rosebud
Messages
25
Reaction score
0
How do I find all the different combinations of the point (x,y,z) when x,y, and z can be either positive and negative? For example, what I'm trying to solve is (+,+,+), (+,+,-), (+,-,-), etc. How do I find out how many different points there are and the sign of each variable for each distinct point?
 
Mathematics news on Phys.org
Rosebud said:
How do I find all the different combinations of the point (x,y,z) when x,y, and z can be either positive and negative? For example, what I'm trying to solve is (+,+,+), (+,+,-), (+,-,-), etc. How do I find out how many different points there are and the sign of each variable for each distinct point?
In 3D coordinates, how many "quadrants" are there?
 
There are eight octants. I'm not sure about quadrants. EDIT: OK, I understand now. Thank you.
 
Last edited:
Rosebud said:
There are eight octants. I'm not sure about quadrants.
Right. So how many ways could you have the point positioned, from the point of view of differing signs?
 
As the names imply, in two dimensions there are four "quadrants" and in three dimensions there are eight "octants. In n dimensions there are [itex]2^n[/itex] such subsets.
 
Rosebud said:
There are eight octants. I'm not sure about quadrants.
Yeah, that's why I put "quadrants" in quotes, to mean just "sections", which you more appropriately identified as octants.