Math 300

Groupwork

Combination Problems

Dr. Wilson

 

2. 8 points are arranged in a circle and each point is joined to each other point by a line. How many lines are needed?

 

 

We could look at the picture and count the lines. But the point of this problem is that a line is determined by 2 points, so there are as many lines as there are 2 element subsets of the set of 8 points.