A crescent-shaped portion of a plane or sphere bounded by two arcs of circles.
[Latin lūna, moon; see leuk- in the Appendix of Indo-European roots.]
(click for a larger image)lune
The area of this lune, the outer arc of which is a semicircle centered at M and the inner arc of which is a quarter circle centered at C, is equal to the area of the triangle ABC.
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