In two papers of Terrel and Penrose, the concept of Terrel effect were presented. Both of the papers say that "the plane of projection is expanded by a certain factor, which is equal to Doppler factor for certain cases." Now does it mean the area of the projected plane is expanded by that factor? But according to Terrel's paper, which used relativistic aberration to derive, each side of an infinitesimal rectangle is increased by that factor(the subtended angle of the sides increases therefore the sides). If that's the case, shouldn't the area of the projection plane be expanded by the square of that factor??