What kind of figure can be formed by 3 collinear points and one non-collinear point?
Triangle
By joining any 2 points a line can be formed. By joining any 2 collinear points and a third non-collinear point, we get a triangle. To form a quadrilateral, at least 3 non-collinear points are needed, but we don't have 4 non-collinear points.