UPSC NDA Math Model Paper 8

Given, any four points in a plane such that each line contains at least two of these points.
The maximum number of straight lines that can be drawn with any four points in a plane such that each line contains at least two of these points =4C2
=

4!

(4−2)!2!

=

2!3.4

2!2!

=6
Hence, the maximum number of straight lines that can be drawn with any four points in a plane such that each line contains at least two of these points is 6.