The study of the inverses of the
six trig functions.
Technical note: Since none of the six trig
functions sine, cosine, tangent, cosecant, secant,
and cotangent are one-to-one,
their inverses are not functions.
Each trig function can
have its domain restricted,
however, in order to make its inverse a function. Some mathematicians
write these restricted trig functions and their inverses with
an initial capital letter (e.g. Cos or Cos-1).
However, most mathematicians do not follow this practice. This
website does not distinguish between capitalized and uncapitalized