Three points in a $3$D space define a plane. A vector perpendicular to any vector lying in that plane is called a normal vector.

Assign planeNormal with the normal vector to the plane defined by the point$1,$ point$2,$ and point$3.$ To find the normal vector,

A vector lying in the plane is found by subtracting the first point's coordinates from the second point.

A second vector lying in the plane is found by subtracting the first point's coordinates from the third point.

The normal vector is found by calculating the cross product of two vectors lying in the plane.

Ex: If point$1,$ point$2,$ and point$3$ are $[0,0,1],[2,2,3],$ and $[0,3,1],$ respectively, then planeNormal is $[-6,0,6].$