Checking to see if 3 points are on the same line

Question

I want to know a piece of a code which can actually tell me if 3 points in a 2D space are on the same line or not. A pseudo-code is also sufficient but Python is better.

Answer 1

You can check if the area of the ABC triangle is 0:

[ Ax * (By - Cy) + Bx * (Cy - Ay) + Cx * (Ay - By) ] / 2

Of course, you don't actually need to divide by 2.