\(n\) PointsDiscrete Mathematics Level 3
\(A\),\(B\),\(C\) and \(D\) are the vertices of the rectangle.
Let \(n\geq 1\) point(s) be marked on the rectangle in such a way that there are no 3 collinear points.
3 points are chosen at random.
What is the probability of forming a triangle where point \(B\) isn't one of the vertices?