Prove that points `hati+2hatj-3hatk, 2hati-hatj+hatk and 2hati+5hatj-hatk` form a triangle in space.

Explanation

Given points are `A(hati+2hatj-3hatk), B(2hati-hatj+hatk), C(2hati+5hatj-hatk)`
`" ""Vectors "vec(AB)=hati-3hatj+4hatk and vec(AC)=hati+3hatj+2hatkk`
Clearly vectors `vec(AB) and vec(AC)` are non-collinear as there does not exist any real `lamda` for which `vec(AB)=lamdavec(AC)`.
`" "` Hence, vecors `vec(AB) and vec(AC)` or the given three points form a triangle.