0 a function (= a mathematical relation) of an angle that is the reciprocal of sine --
1 a function (= mathematical relation) of an angle that is the reciprocal (= number) of sine --
The two expressions are derived from identities involving the cotangent and cosecant functions.
If is an integer multiple of, then the cotangent and cosecant functions above diverge.
Later aerial reflectors were actually shaped with a cosecant-squared curvature.
The function is the multiplicative inverse to the sine, and is called the cosecant.
The cosine, cotangent, and cosecant are so named because they are respectively the sine, tangent, and secant of the complementary angle abbreviated to co-.