points_colinear

This code checks if 3 points are collinear or not by calculating the determinant of those points

Three or more points P_1, P_2, P_3, ..., are said to be collinear if they lie on a single straight line L. A line on which points lie, especially if it is related to a geometric figure such as a triangle, is sometimes called an axis. You can check further details in this link: http://mathworld.wolfram.com/Collinear.html