Four points A, B, C, and D are coplanar, but only two at a time are collinear. Suppose a line is drawn through each pair of points. How many lines can you draw?

a)0
b)2
c)4
d)6

Question

Four points A, B, C, and D are coplanar, but only two at a time are collinear. Suppose a line is drawn through each pair of points. How many lines can you draw?

a)0
b)2
c)4
d)6

anonymous · Answer

Draw it on a piece of paper.  It's easy enough to just add them up.  There IS a very simple pattern and formula that you can figure out quickly.  Just start with 1 point.  Mark how many lines you can make.  Then your 2nd point.  Mark how many lines you can make with that.  Do it a couple more times and you should see the pattern.