# $$n$$ Points

$$A$$,$$B$$,$$C$$ 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?

×