Given three collinear points A,B,C , with B between A & C, four different rays can be named using these points AB, BA, BC, & CB. How many different rays can be named?
The total number of rays that can be named by 3 points is the number of permutations of 3 objects taken 2 at a time: 3!/(3-2)! = 6. The 6 rays that can be named are ...
