All that Lady Belinda need do was this: She should measure from A to B,
fold her tape in four and mark off the point E, which is thus one
quarter of the side. Then, in the same way, mark off the point F,
one-fourth of the side AD Now, if she makes EG equal to AF, and GH equal
to EF, then AH is the required width for the path in order that the bed
shall be exactly half the area of the garden. An exact numerical
measurement can only be obtained when the sum of the squares of the two
sides is a square number. Thus, if the garden measured 12 poles by 5
poles (where the squares of 12 and 5, 144 and 25, sum to 169, the square
of 13), then 12 added to 5, less 13, would equal four, and a quarter of
this, 1 pole, would be the width of the path.