Arc symbol (⌒)

How to read it

Two points on a circle cut it into two arcs, a shorter minor arc and a longer major arc. Henry Africk’s Elementary College Geometry (CUNY) reads the arc over AB as the minor arc unless the text says otherwise, and names the major arc with a third point on it, the arc over ACB. The number of degrees in an arc is the number of degrees in the central angle that cuts it off, and Africk keeps a separate sign, an equals sign with a small circle on top, for “equal in degrees”, saving the plain = for arc length.

Also searched as: ⌒, ⌒AB, arc AB, curve over letters, major arc, minor arc.

Look-alikes

Unicode encodes ⌒ ARC (U+2312) in its Miscellaneous Technical block with the gloss “position of any line”, its meaning on engineering drawings, where the open arc is the profile of a line tolerance: the UK National Physical Laboratory’s guide describes its zone as lying between two lines either side of the designed outline. ⌓ SEGMENT (U+2313), the arc closed by a straight line, is the profile of a surface. Unicode cross-refers ⌒ to the upper half circle ◠ (U+25E0). Over a pair of letters in a geometry problem, the arc names part of a circle; in a feature control frame, it is a tolerance.