Question

Determine if the points (1,5),(2,3) and (−2,−11) are collinear , by distance formula.

Answer 1

A(1,5), B(2,3) and C(−2,−11)

Now, AB=√(1²)+(2²)=√5
BC=√(4²)+(14²)=√212
CA=√(1²)+(16²)=√257

As,CA>BC>AB

If points A, B and C are collinear then AB+BC=CA

But √5+√212≠√257

So they are not collinear.