Two equal semicircles and a circle divided by curved lines
A play on lunes: a common, doubled area; and a circle split into eight curved parts
Leonardo works two small geometric exercises on curved figures. In the first he takes two equal semicircles, discards a part c from one and e from the other, so that the remaining d equals b while a is common to both and counts double. The second, in pencil, describes a circle internally divided into eight curved lines, four of equal curvature and four whose curvature differs from the first.
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Two equal semicircles, labelled a b c d e
Two equal semicircles are set partly one over the other. Removing c from the one and e from the other leaves d equal to b, while the overlap a is common to both figures and therefore counts double, a demonstration on the areas of lunes.
Circle divided by eight curved lines
A circle is divided internally by curved lines into eight portions, four of equal curvature and four whose curvature differs from the first set, exploring how curved cuts partition a circular area.