Let (C) a circle . A is a point outside (C). Let (D1), (D2) two tangents issued from A. (D1) is tangent at K and (D2) is tangent at L respectively. Let (D) a straight line passing through A, between (D1) and (D2). The meeting points with (C) are M and N respectively. Let (LP) the parralel at (D) issued from L, where P is the intersection with(C). Prouve that (PK) intersect [MN] at his middle.