How can you plant seven straight rows of trees with six trees per row such that twenty-one trees are planted in total?

How can you plant nine straight rows of trees with three trees per row such that nine trees are planted in total?

(0,0),(1,0),(2,0),(.5,1),(1,1),(1.5,1),(0,2),(1,2),(2,2)

. . .
 ...
. . .

This arrangement creates not nine, but ten rows.

Posted by Tristan on 2006-10-21 17:08:59