A.+4″ B.-4″ C.+8″ D.-8″
A.45° B.225° C.135° D.315°
A.DAB=71.71m,αAB=137° B.DAB=80.81m,αAB=130° C.DAB=70.71m,αAB=135° D.DAB=70.11m,αAB=125°