sentences:  Line DN meets the perpendicular bisector of AB at Q.From Q construct a line parallel to FK to intersect ray MI at R. As shown in the figure, using O which is the center of the rectangle ABCD, as a center of rotation for 180°, one can make the fundamental region for the tiling.First, divide the right angle into five congruent angles, a arbitrary point P was selected on the first ray counterclockwise.