The boundary of a simply connected domain at an inner tangent point
John N. Marafino · Pacific Journal of Mathematics · 1992
Let T* be the set of accessible boundary points at which the inner tangent to dD exists.That is, if a e T* and w(a) represents its complex coordinate, then there exists a unique v[d), 0 0 (e 0 such that Δ = {w(ά) + pe w : 0 a as w -> w(a), w G Δ.