Jonathan T. answered • 05/29/19

Fun and Patient Calculus, Linear Algebra, and Differential Eq. Tutor

There are multiple ways to approach this problem.

You can determine if the lines created between the points a,b and a, c, and b,c are all multiples of each other so the solution to them is infinite.

You can determine if the angles between the lines are zero or nonzero.

Point being, your preferred solution would be better asked if you specify the course you are in i.e. it is algebra, trig, calc, linear algebra, but I think it is geometry for your case so if you could specify the technique you are at, that would help clarify.