Answer with Explanation:
As, euclidean geometry that is axioms and postulates is valid for two as well three dimensional space.
If there are three points in Space, then
1. If all of them are Collinear, they will form a straight line segment.
2. Otherwise ,they will form a closed three dimensional shape similar to triangle in in two dimensional.
It can be explained by, taking stars as a point in the space. If three stars lie in the same line, and if you join them ,it will form a line segment, otherwise it will be in the shape of triangle.