Let AB extended intersect DC extended at point E We now have right triangle BEC with E = 90 degrees
For triangle BEC: Exterior angle at E = 90 Exterior angle at C = 148 (given) Exterior angle of all polygons add up to 360 degrees Exterior angle at B = 360−148−90 = 122
So in quadrilateral ABCD B = 122 D = 360−44−148−122 = 46
