A tree is planted at each Lattice Point in a circular orchard which has Center at the Origin and Radius . If the radius of trees exceeds units, one is unable to see out of the orchard in any direction. However, if the Radii of the trees are , one can see out at certain Angles.
See also Lattice Point, Orchard-Planting Problem, Visibility
Honsberger, R. ``The Orchard Problem.'' Ch. 4 in Mathematical Gems I.
Washington, DC: Math. Assoc. Amer., pp. 43-52, 1973.