Question

Are the points on a triangle co linear??

Answer 1

No, to be colinear the points must be on the same line.
A triangle is formed with 3 distinct lines

Answer 2

Yeah dumbcow was right and you can check whether three points are collinear or not by finding the area of the triangle formed by the three points using the point formula
\[1/2[x1(y2−y3)+x2(y3−y1)+x3(y1−y2)]\]
where (x1,y1),(x2,y2),(x3,y3) are three vertices of the triangle.
If area=0, then the points are collinear or else they form a triangle...