In this work we develop a unified approach for numerical
approximation and fast solution of classical integral equations on
open arcs. The approximation is obtained applying the cosine
transform and fully discrete trigonometric collocation together with
an asymptotic approximation of the operator. The computed
approximation is of optimal accuracy order in a large scale of
Sobolev norms, and it can be obtained in

arithmetical
operations. Our results cover logarithmic singular integral
equations, Cauchy singular integral equations, as well as
hypersingular integral equations.