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?

Arrange 7 points equally around a circle (about 51.42857 degrees apart). Join straight lines connecting each pair that is 154.2857 degrees apart, making a 7-pointed star. At each intersection, including the points of the star, plant a tree.

Posted by Charlie on 2006-10-21 19:27:58