The illustration shows the figure known in mathematics as;
lune of Hippocrates,
In geometry, the lune of Hippocrates, named after Hippocrates of Chios, is a lune bounded by arcs of two circles, the smaller of which has as its diameter a chord spanning a right angle on the larger circle. Equivalently, it is a non-convex plane region bounded by one 180-degree circular arc and one 90-degree circular arc. It is the first curved figure to have its exact area calculated mathematically.
reach: rather globalgeometrymathematics
+1 Very interesting! Kampfgraff
+1 Very interesting! Fabienne
+1 Very interesting! M