do 4 points make something coplanar? what about 3?

Question

geometry..

Answer 1

3 points are coplanar because if you draw lines between the points they will define a plane with the cross lines intersecting at each point. This must be visualized in 3-dimensional space to see it.

4 Points may not be coplanar unless they meet special criteria, which can be tested mathematically by expressing the plane that intersects three of the points, and then testing the fourth to see if it intersects the plane.