I give two pleasing arrangements of the trees. In each case there are twelve straight rows with five trees in every row.
[Illustration: Figure 1, Figure 2.]
209.--THE TWENTY-ONE TREES.
From Amusements in Mathematics by Henry Ernest Dudeney.
From Amusements in Mathematics by Henry Ernest Dudeney.
I give two pleasing arrangements of the trees. In each case there are twelve straight rows with five trees in every row.
[Illustration: Figure 1, Figure 2.]