On Distortion at the Boundary of a Conformal Map.

o but containing the line segment 0 _ w < 1, and whose boundary possesses at the point w = 1 forward and backward tangents making equal angles a/2 (>0) with the negative direction of the axis of reals. Let thefunction w = f(z) map the region R, :x < 1 of the z(= x + iy)-plane onto Rw in such a way that we have f(O) = 0, f(1) = 1. Let the sequence xn, 0 < xn < 1, approach unity. Then for z on any closed bounded set in Rz we have uniformly