The annular region bounded by was then denoted by Ωh and closed polygonal line Γh with vertices and Th was regular triangulation of Ωh with triangles T of diameter hT so that .
Entonces denotamos con Ωh la región anular acotada por cost,sen t Γ= y la línea poligonal cerrada Γh con vértices y sea Th una triangulación regular de Ωh con triángulos T de diámetro hT tal que .