Question

How many non-collinear points are always coplanar?

Answer 1

It is three non-collinear points that form a plane.

Explanation:

It is three non-collinear points that form a plane.

Observe that two non-collinear points make a straight line i.e. `2D`

and in `3D` you need three non-collinear points to form a plane.

Let the points be `A,B` and `C` and let us form avecrors `vec(AB)` and `vec(AC)`.

The vector `vec(AB)xxvec(AC)`, the cross product of `vec(AB)` and `vec(AC)` is a vector perpendicular to both.

The plane passing through `A` and perpendicular to `vec(AB)xxvec(AC)` is the plane formed by these three points.