Determine whether 3 Points are Collinear: Are these points collinear?

A(1, -3, 2), B(4, 2, 5), C(-2, 1, -3).

If the points are collinear, the sum of the distances between two pairs of points equals the distance between the third pair of points.

The distance formula for 3 dimensions must be used here:

. Applying this we get

Hence, we do not have AB + AC = BC, and the points are not collinear, but determine a triangle.