The key to this problem is the understanding of translation, which I understand as horizontal movement, that is, point B (2,0) translates to point D (-d,0), point A (0,3) translates to point C (-d-2 d-2,3), and triangles BCD and BD are X-axis. The absolute value of the ordinate of point C is the height of the triangle, that is, the height is 3 and the area is 3.